Touch panel, display panel, and display unit

ABSTRACT

A touch panel, a display panel, and a display unit achieving prevention of erroneous detection caused by external noise, are provided. The touch panel includes: a plurality of detection scan electrodes extending in a first direction; and a plurality of detection electrodes facing the plurality of detection scan electrodes and extending in a second direction which intersects the first direction. A ratio of fringe capacitance to total capacitance between one or more selected detection scan electrodes and a first detection electrode is different from a ratio of fringe capacitance to total capacitance between the one or more selected detection scan electrodes and a second detection electrode. The one or more selected detection scan electrodes are selected, in a desired unit, from the plurality of detection scan electrodes, to be supplied with a selection pulse, and each of the first and the second detection electrodes is selected from the plurality of detection electrodes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a touch panel, a display panel, and adisplay unit enabling information to be entered by being touched with anobject such as a finger or pen.

2. Description of the Related Art

Techniques of entering information by touch with a finger or the likeare known. Among them, a technique attracting particular attention is adisplay device capable of entering information by touching variousbuttons displayed on a display with a finger or the like in a mannersimilar to the case of touching normal buttons with a finger or thelike. The technique allows the display and the buttons to be commonlyused and therefore brings large advantages of smaller space andreduction in the number of parts.

Various types of touch sensors that detect a touch of a finger or thelike exist. A popularized touch sensor is, for example, of anelectrostatic capacitance type. A touch sensor of this type catches, bya capacitive element, a change occurring in the surface electric fieldof a panel when a touch panel is touched with a finger or the like, anddetects a touch of a finger or the like (for reference, see JapaneseUnexamined Patent Application Publication No. 2008-9750).

SUMMARY OF THE INVENTION

In the detecting method described above, a change in the surfaceelectric field of the panel is read by a capacitive element.Consequently, in the case where noise from the outside enters thecapacitive element, the surface electric field of the panel changes dueto the noise, and there is a possibility that touch of a finger iserroneously detected. In particular, in the case where the user of adisplay device plays the role of an antenna and catches external noise,there is a problem such that when the user touches the panel with afinger or the like, the external noise is transmitted via the finger orthe like to the panel, the surface electric field of the panel changes,and it causes erroneous detection.

It is therefore desirable to provide a touch panel, a display panel, anda display unit capable of eliminating erroneous detection caused byexternal noise.

A touch panel according to an embodiment of the invention includes aplurality of detection scan electrodes extending in a first direction;and a plurality of detection electrodes provided to face the pluralityof detection scan electrodes and extending in a second direction whichintersects the first direction, the plurality of detection electrodeshaving a first detection electrode and a second detection electrode. Aratio of fringe capacitance to total capacitance between one or moreselected detection scan electrodes and the first detection electrode isdifferent from a ratio of fringe capacitance to total capacitancebetween the one or more selected detection scan electrodes and thesecond detection electrode, the one or more selected detection scanelectrodes being selected, in a desired unit, from the plurality ofdetection scan electrodes, to be supplied with a selection pulse, andeach of the first detection electrode and the second detection electrodebeing selected from the plurality of detection electrodes.

As used herein, the term “fringe capacitance” corresponds to, forexample, a capacitance generated by an electric field (round electricfield) around a gap between two parallel plates when a voltage isapplied between the two parallel plate electrodes facing each other. Asused herein, the term “total capacitance” in “total capacitance betweenthe one or more selected detection scan electrodes and the seconddetection electrode” corresponds to, for example, a capacitance obtainedby totaling a capacitance (parallel plate capacitance) formed by theelectric field in the gap between two parallel plates and thecapacitance (fringe capacitance) formed by the round electric field whenthe voltage is applied between the two parallel plate electrodes facingeach other.

A display panel according to an embodiment of the invention includes: aplurality of pixel electrodes; a common electrode provided to face theplurality of pixel electrodes; a display function layer having a displayfunction; a plurality of detection scan electrodes extending in a firstdirection; and a plurality of detection electrodes provided to face theplurality of detection scan electrodes and extending in a seconddirection which intersects the first direction, the plurality ofdetection electrodes having a first detection electrode and a seconddetection electrode. A ratio of fringe capacitance to total capacitancebetween one or more selected detection scan electrodes and the firstdetection electrode is different from a ratio of fringe capacitance tototal capacitance between the one or more selected detection scanelectrodes and the second detection electrode, the one or more selecteddetection scan electrodes being selected, in a desired unit, from theplurality of detection scan electrodes, to be supplied with a selectionpulse, and each of the first detection electrode and the seconddetection electrode being selected from the plurality of detectionelectrodes.

Another display panel according to an embodiment of the inventionincludes: a plurality of pixel electrodes; a plurality of commonelectrodes provided to face the plurality of pixel electrodes andextending in a first direction; a display function layer having adisplay function; and a plurality of detection electrodes provided toface the plurality of the common electrodes and extending in a seconddirection which intersects the first direction, the plurality ofdetection electrodes having a first detection electrode and a seconddetection electrode. A ratio of fringe capacitance to total capacitancebetween one or more selected common electrodes and the first detectionelectrode is different from a ratio of fringe capacitance to totalcapacitance between the one or more selected common electrodes and thesecond detection electrode, the one or more selected common electrodesbeing selected, in a desired unit, from the plurality of commonelectrodes, to be supplied with a selection pulse, and each of the firstdetection electrode and the second detection electrode being selectedfrom the plurality of detection electrodes.

A display unit according to an embodiment of the invention includes: aplurality of pixel electrodes; a common electrode provided to face theplurality of pixel electrodes; a display function layer having a displayfunction; a plurality of detection scan electrodes extending in a firstdirection; a plurality of detection electrodes provided to face theplurality of detection scan electrodes and extending in a seconddirection which intersects the first direction, the plurality ofdetection electrodes having a first detection electrode and a seconddetection electrode; a first drive section allowing the display functionof the display function layer to be performed by applying a signalvoltage corresponding to a video signal between each of the pixelelectrode and the common electrode; a second drive section applying aselection pulse to the plurality of detection scan electrodes; and adetection section detecting an external proximity object on the basis ofa detection signals obtained from the plurality of detection electrodes.A ratio of fringe capacitance to total capacitance between one or moreselected detection scan electrodes and the first detection electrode isdifferent from a ratio of fringe capacitance to total capacitancebetween the one or more selected detection scan electrodes and thesecond detection electrode, the one or more selected detection scanelectrodes being selected, in a desired unit, from the plurality ofdetection scan electrodes by the second drive section, to be suppliedwith a selection pulse, and each of the first detection electrode andthe second detection electrode being selected from the plurality ofdetection electrodes.

Another display unit according to an embodiment of the inventionincludes: a plurality of pixel electrodes; a plurality of commonelectrodes provided to face the plurality of pixel electrodes andextending in a first direction; a display function layer having adisplay function; a plurality of detection electrodes provided to facethe plurality of the common electrodes and extending in a seconddirection which intersects the first direction, the plurality ofdetection electrodes having a first detection electrode and a seconddetection electrode; a drive section allowing the display function ofthe display function layer to be performed by applying a signal voltagecorresponding to a video signal between each of the pixel electrode andthe common electrode, and applying a selection pulse to the plurality ofcommon electrodes; and a detection section detecting an externalproximity object on the basis of a detection signals obtained from theplurality of detection electrodes. A ratio of fringe capacitance tototal capacitance between one or more selected common electrodes and thefirst detection electrode is different from a ratio of fringecapacitance to total capacitance between the one or more selected commonelectrodes and the second detection electrode, the one or more selectedcommon electrodes being selected, in a desired unit, from the pluralityof common electrodes by the second drive section, to be supplied with aselection pulse, and each of the first detection electrode and thesecond detection electrode being selected from the plurality ofdetection electrodes.

In the touch panel, the display panels, and the display units accordingto the embodiments of the present invention, the ratio of the fringecapacitance to the total capacitance between the one or more selecteddetection scan electrodes or common electrodes) and the first detectionelectrode is different from the ratio of the fringe capacitance to thetotal capacitance between the one or more selected detection scanelectrodes or common electrodes) and the second detection electrode. Theratio of the fringe capacitance to the capacitance between the one ormore selected detection scan electrodes (or common electrodes) and onedetection electrode corresponds to a sensitivity to thecontact/noncontact state in that detection electrode. When the ratio ishigh, the sensitivity to the contact/noncontact state is high. When theratio is low, the sensitivity to the contact/noncontact state is low.That is, in the embodiments of the present invention, at least two kindsof detection electrodes whose sensitivities to the contact/noncontactstate are different are provided. Thus, when the one or more selecteddetection scan electrodes (or common electrodes) is/are selected in thedesired unit, a signal level of the higher ratio of the fringecapacitance of either the detection signal obtained from the firstdetection electrode or the detection signal obtained from the seconddetection electrode is influenced by the external proximity objecttouching the touch panel and fluctuates largely more than a signal levelof the lower ratio of the fringe capacitance. Hence, for example, byobtaining the difference between the detection signal obtained from thefirst detection electrode and the detection signal obtained from thesecond detection electrode, external noise is eliminated from thedetection signal.

Preferably, a first capacitance between the external proximity objecttouching the touch panel and the first detection electrode, and a secondcapacitance between the external proximity object touching the touchpanel and the second detection electrode, are almost equal to eachother. In this case, the sensitivity to the external noise in the firstdetection electrode and that in the second detection electrode arealmost equal to each other. Thus, for example, by simply obtaining thedifference between the detection signal obtained from the firstdetection electrode and the detection signal obtained from the seconddetection electrode, the external noise is eliminated from the detectionsignals. Incidentally, the first capacitance and the second capacitancemay be largely different from each other. In this case, for example, bycorrecting the signal level of the detection signal in consideration ofan amount of discrepancy therebetween and deriving the difference byusing the corrected detection signal, the external noise is eliminatedfrom the detection signal.

In the touch panel, the display panels, and the display units accordingto the embodiments of the present invention, the ratio of the fringecapacitance to the total capacitance between the one or more selecteddetection scan electrodes or common electrodes) and the first detectionelectrode is made different from the ratio of the fringe capacitance tothe total capacitance between the one or more selected scan electrodesand the second detection electrode, making it possible to eliminate theexternal noise from the detection signal. Therefore, it is possible toeliminate erroneous detection caused by the external noise.

Other and further objects, features and advantages of the invention willappear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams for explaining the principle of operationof a touch detection method used in a liquid crystal display deviceaccording to an embodiment of the present invention, and illustrating anon-contact state.

FIGS. 2A and 2B are diagrams for explaining the principle of operationof the touch detection method used in the liquid crystal display deviceaccording to the embodiment of the present invention, and illustrating afinger contact state.

FIG. 3 is a diagram for explaining the principle of operation of thetouch detection method used in the liquid crystal display deviceaccording to the embodiment of the present invention, and illustratingan example of waveform of a drive signal and a detection signal of atouch sensor.

FIG. 4 is a diagram illustrating a schematic configuration of a liquidcrystal display device according to a first embodiment of the invention.

FIG. 5 is a diagram illustrating an example of a schematic configurationof pixels in a liquid crystal display panel shown in FIG. 4.

FIG. 6 is a diagram illustrating an example of a sectional configurationof the liquid crystal display panel shown in FIG. 4.

FIG. 7 is a diagram illustrating an example of a top face configurationof a touch panel shown in FIG. 4.

FIG. 8 is a diagram illustrating an example of a sectional configurationof the touch panel shown in FIG. 4.

FIG. 9 is a diagram illustrating another example of the top faceconfiguration of the touch panel shown in FIG. 4.

FIG. 10 is a diagram illustrating another example of the top faceconfiguration of the touch panel shown in FIG. 4.

FIG. 11 is a diagram illustrating an example of a schematicconfiguration of a scan line drive circuit shown in FIG. 4.

FIG. 12 is a diagram illustrating an example of a schematicconfiguration of a detection circuit shown in FIG. 4.

FIG. 13 is a schematic diagram for explaining fringe capacitance in thetouch panel illustrated in FIG. 7.

FIG. 14 is a diagram illustrating an example of waveforms of signals inthe touch panel in FIGS. 7, 9, and 10.

FIG. 15 is a diagram illustrating another example of the top faceconfiguration of the touch panel shown in FIG. 4.

FIG. 16 is a diagram illustrating another example of a schematicconfiguration of the detection circuit shown in FIG. 4.

FIG. 17 is a diagram illustrating an example of the top faceconfiguration of a touch panel mounted on a liquid crystal displaydevice according to a second embodiment of the invention.

FIG. 18 is a diagram illustrating an example of waveforms of signals inthe touch panel of FIG. 17.

FIG. 19 is a diagram illustrating an example of the top faceconfiguration of a touch panel mounted on a liquid crystal displaydevice according to a third embodiment of the invention.

FIG. 20 is a diagram illustrating an example of the top faceconfiguration of a touch panel mounted on a liquid crystal displaydevice according to a fourth embodiment of the invention.

FIG. 21 is a diagram illustrating a schematic configuration of a liquidcrystal display device according to a fifth embodiment of the invention.

FIG. 22 is a diagram illustrating an example of a schematicconfiguration of pixels in a liquid crystal display panel shown in FIG.21.

FIG. 23 is a diagram illustrating another example of a sectionalconfiguration of the liquid crystal display panel shown in FIG. 21.

FIG. 24 is a diagram illustrating another example of a sectionalconfiguration of the liquid crystal display panel shown in FIG. 21.

FIG. 25 is a diagram illustrating an example of the top faceconfiguration of the liquid crystal display panel shown in FIG. 21.

FIG. 26 is a diagram illustrating another example of the top faceconfiguration of the liquid crystal display panel shown in FIG. 21.

FIG. 27 is a diagram illustrating another example of the top faceconfiguration of the liquid crystal display panel shown in FIG. 21.

FIG. 28 is a conceptual diagram for explaining fringe capacitance in theliquid crystal display panels shown in FIGS. 25, 26, and 27.

FIG. 29 is a diagram illustrating another example of the top faceconfiguration of the liquid crystal display panel shown in FIG. 21.

FIG. 30 is a diagram illustrating an example of the top faceconfiguration of a touch panel mounted on a liquid crystal displaydevice according to a sixth embodiment of the invention.

FIG. 31 is perspective view illustrating an appearance in applicationexample 1 of the display device in the foregoing embodiments and thelike.

FIG. 32A is a perspective view of the appearance from the front side inapplication example 2, and FIG. 32B is a perspective view of theappearance from the back side.

FIG. 33 is a perspective view illustrating the appearance of applicationexample 3.

FIG. 34 is a perspective view illustrating the appearance of applicationexample 4.

FIG. 35A is a front view of an open state of application example 5, FIG.35B is a side view, FIG. 35C is a front view of a closed state, FIG. 35Dis a left side view, FIG. 35E is a right side view, FIG. 35F is a topview, and FIG. 35G is a bottom view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described indetail below with reference to the drawings. Description will be givenin the following order.

-   1. Basic principle of touch detection method-   2. First embodiment

An example that touch sensor is provided in touch panel.

An example that two kinds of detection electrodes having differentshapes are provided.

An example that sensitivity of detection electrode is constantregardless of scan electrode.

-   3. Modification of first embodiment

An example that output adjustment circuit is provided.

-   4. Second embodiment

An example that touch sensor is provided in touch panel.

An example that two kinds of detection electrodes having differentshapes are provided.

An example that sensitivity of detection electrode varies according toscan electrode.

-   5. Modification of second embodiment

An example that output adjustment circuit is provided.

-   6. Third embodiment

An example that touch sensor is provided in touch panel.

An example that detection electrodes having the same shape are provided.

An example that fringe capacitance increases in predetermined detectionelectrode.

-   7. Fourth embodiment

An example that touch sensor is provided in touch panel.

An example that detection electrodes having the same shape are provided.

An example that fringe capacitance is equal in all of detectionelectrodes.

-   8. Fifth embodiment

An example that touch sensor is provided in liquid crystal displaypanel.

An example that two kinds of detection electrodes having differentshapes are provided.

An example that sensitivity of detection electrode is constantregardless of scan electrode.

-   9. Modification of fifth embodiment

An example that output adjustment circuit is provided.

-   10. Sixth embodiment

An example that touch sensor is provided in liquid crystal displaypanel.

An example that two kinds of detection electrodes having differentshapes are provided.

An example that sensitivity of detection electrode varies according toscan electrode.

-   11. Modification of sixth embodiment

An example that output adjustment circuit is provided.

-   12. Application examples

Examples that the liquid crystal display devices of the embodiments areapplied to electronic devices.

[Basic Principle of Touch Detection Method]

First, the basic principle of a touch detection method used in a displaydevice of an embodiment will be described below. This touch detectionmethod is embodied as a touch sensor of an electrostatic capacitancetype. FIG. 1A schematically illustrates the touch sensor. FIG. 1Bschematically illustrates an equivalent circuit of the touch sensorillustrated in FIG. 1A and a peripheral circuit connected to the touchsensor. The touch sensor has a dielectric 101 and a pair of electrodes102 and 103 disposed opposing to each other while sandwiching thedielectric 101, and expressed as a capacitive element 104 in theequivalent circuit as shown in FIG. 1B.

One end (electrode 102) of the capacitive element 104 is connected to anAC signal source 105. The other end (electrode 103) of the capacitiveelement 104 is connected to a voltage detection circuit 106 and,further, is connected to a reference potential line 108 via a resistor107. The AC signal source 105 outputs an AC rectangular wave Sg ofpredetermined frequency (for example, a few kHz to tens kHz). Thevoltage detection circuit 106 detects a crest value of an input signaland, further, determines whether the touch sensor is touched with afinger or not on the basis of the detection voltage thereof. Thereference potential line 108 is, for example, electrically connected toa member (for example, a ground layer of a printed board or a conductivecasing) to which a potential as a reference of a circuit operation isapplied in a device on which the touch sensor is mounted. When thereference potential line 108 is connected to the member, the potentialin the reference potential line 108 is equal to that of the member (thereference potential). The reference potential is, for example, theground potential.

In the touch sensor, when the AC rectangular wave Sg (Part (B) of FIG.3) is applied from the AC signal source 105 to the electrode 102, anoutput waveform (detection signal Vdet) as shown in Part (A) of FIG. 3appears.

In a state where the touch sensor is not touched with an object such asa finger (FIG. 1A), as shown in FIG. 1B, current Io according to thecapacitance value of the capacitive element 104 flows in accordance withcharging/discharging of the capacitive element 104. The potentialwaveform at this time on the side of the electrode 103 of the capacitiveelement 104 becomes like a waveform Vo of Part (A) of FIG. 3, and isdetected by the voltage detection circuit 106.

On the other hand, in a state where the touch sensor is touched with anobject such as a finger (FIG. 2A), as shown in FIG. 2B, a capacitiveelement 109 formed by the object such as the finger is added to thecapacitive element 104 in series. In this state, currents I₁ and I₂ flowaccording to charging/discharging of the capacitive elements 104 and109, respectively. At this time, the potential waveform in the electrode103 becomes, for example, a waveform V₁ of Part (A) of FIG. 3, and isdetected by the voltage detection circuit 106. The potential of theelectrode 103 becomes a divided potential determined by the values ofthe currents I₁ and I₂ flowing in the capacitive elements 104 and 109.Consequently, the waveform V₁ becomes a value smaller than the waveformV₀ in the non-contact state. After that, by the voltage detectioncircuit 106, the detected voltage and predetermined threshold voltageV_(th) are compared with each other. When the detected voltage is equalto or less than the threshold voltage Vth, the non-contact state isdetermined. On the other hand, when the detected voltage is larger thanthe threshold voltage Vth, the contact state is determined. In such amanner, a touch is detected.

First Embodiment

FIG. 4 illustrates an example of a sectional configuration of a liquidcrystal display device 1 according to a first embodiment of theinvention. The liquid crystal display device 1 is a liquid crystaldisplay device with a touch sensor. As a display element, a liquidcrystal display element is provided. Further, on the surface of theliquid crystal display element, a touch sensor of the electrostaticcapacitance type is provided separately from the liquid crystal displayelement.

The liquid crystal display device 1 has, for example, as illustrated inFIG. 4, a liquid crystal display panel 10, a touch panel 20, a backlight30, and a peripheral circuit 40. The touch panel 20 is disposed on theside of an observer (front) of the liquid crystal display panel 10, andthe backlight 30 is disposed on the rear side of the liquid crystaldisplay panel 10.

[Liquid Crystal Display Panel 10]

The liquid crystal display panel 10 displays a video image bytransmitting or modulating light from the lights source (backlight 30)by changing arrangement of liquid crystal molecules. The liquid crystaldisplay panel 10 is, for example, a transmission-type display panel inwhich a plurality of pixels 11 (refer to FIG. 5) disposed in matrix aredriven in accordance with a video signal 40A. For example, as shown inFIG. 5, the liquid crystal display panel 10 has a plurality of scanlines WSL1 disposed as rows and a plurality of signal lines DTL disposedas columns. The plurality of pixels 11 are disposed in matrix incorrespondence with intersections between the scan lines WSL1 and thesignal lines DTL. In the liquid crystal display panel 10, further, forexample, as shown in FIG. 5, a plurality of common connection lines COMare disposed as rows. For example, each of the common connection linesCOM is arranged for one row of pixels 11.

Each pixel 11 includes, for example, as shown in FIG. 5, a liquidcrystal element 12 and a transistor 13. One end of the liquid crystalelement 12 is connected to the drain of the transistor 13, and the otherend of the liquid crystal element 12 is connected to the commonconnection line COM. The gate of the transistor 13 is connected to thescan line WSL1, and the source of the transistor 13 is connected to thesignal line DTL. The liquid crystal element 12 modulates light passingtherethrough in accordance with a state of electric field, and isprovided in the liquid crystal display panel 10. The internalconfiguration of the liquid crystal element 12 will be described indetail later. The transistor 13 is provided to drive the liquid crystalelement 12, and is structured by, for example, a TFT (Thin FilmTransistor).

The liquid crystal display panel 10 has, for example, as illustrated inFIG. 6, a liquid crystal layer 130 (display function layer), and alight-incidence-side substrate 110 and a light-outgoing-side substrate120 which are disposed opposing to each other while sandwiching theliquid crystal layer 130. The liquid crystal layer 130 modulates lightaccording to the state of the electric field, thereby expressing thedisplay function, and includes, for example, liquid crystal molecules inthe transverse electric mode. Examples of liquid crystal molecules inthe transverse electric mode include electric crystal molecules in theFFS (Fringe Field Switching mode) and liquid crystal molecules in theIPS (In-Plane Switching) mode.

The light-incidence-side substrate 110 is a transparent substratedisposed on the incident side (backlight 30 side) of light from thebacklight 30 in the liquid crystal display panel 10. Thelight-incidence-side substrate 110 has, for example, in order from thebacklight 30 side, a polarizer 111, a transparent substrate 112, aplurality of common electrodes 113, an insulation layer 114, a pluralityof pixel electrodes 115, and an alignment film 116. On the other hand,the light-outgoing-side substrate 120 is a transparent substratedisposed on the outgoing side (observer side) of light modulated by theliquid crystal layer 130 in the liquid crystal display panel 10. Thelight-outgoing-side substrate 120 has, for example, in order from theliquid crystal layer 130 side, an alignment film 121, a color filter122, a transparent substrate 123, and a polarizer 124. The color filter122 may not be provided as necessary.

The liquid crystal element 12 corresponds to, for example, as shown by abroken line in FIG. 6, a portion facing one pixel electrode 115 in theliquid crystal display panel 10. The liquid crystal element 12 includes,for example, the transparent substrate 112, the common electrode 113,the insulation layer 114, the pixel electrode 115, the alignment film116, the liquid crystal layer 130, the alignment film 121, the colorfilter 122, and the transparent substrate 123 in this order.

The polarizers 111 and 124 are a kind of an optical shutter, andtransmit only light in a certain vibration direction (polarized light).The polarizers 111 and 124 are disposed in crossed nicols. For example,the polarizer 111 is disposed so that its transmission axis becomesparallel to the column direction, and the polarizer 124 is disposed sothat its transmission axis becomes parallel to the row direction. Withthis configuration, the liquid crystal display panel 10 transmits orinterrupts light emitted from the backlight 30 via the liquid crystallayer 130.

The transparent substrates 112 and 123 are substrates, for example,plate glass transparent to visible light. In the transparent substrate112, for example, active drive circuits including the transistor, thesignal line DTL, the scan line WSL1, and the common connection line COMare formed.

The common electrode 113 and the pixel electrode 115 are made of amaterial transparent to visible light, which can be, for example, ITO(Indium Tin Oxide). The common electrode 113 is the common connectionline COM itself or a part of the common connection line COM. Theplurality of common electrodes 113 have, for example, a band-like shapeextending in the row direction and are disposed in parallel. The commonelectrode 113 functions, for example, as an electrode common to thepixels 11 by row. Incidentally, the plurality of common electrodes 113may be integrated as a single plate-shaped electrode.

On the other hand, the plurality of pixel electrodes 115 are, forexample, in lattice arrangement or delta arrangement on the transparentsubstrate 112. The pixel electrode 115 functions as, for example, anelectrode for each pixel 11. The plurality of pixel electrodes 115 are,for example, disposed side-by-side via predetermined gaps on a regionopposing one common electrode 113. The electric field formed between thepixel electrode 115 and the common electrode 113 is directed in thetransverse direction (row direction) in the region of the liquid crystallayer 130.

The insulation layer 114 is provided for insulation between the commonelectrode 113 and the pixel electrode 115, and is made of, for example,SiO₂ or the like. The alignment films 116 and 121 are made of a highpolymer material such as polyimide, and have the function of making theliquid crystal included in the liquid crystal layer 130. The alignmentfilms 116 and 121 are subjected to rubbing processes so that, forexample, the rubbing directions thereof become parallel to thetransmission axis of one of the polarizers 111 and 124. For example, therubbing directions of the alignment films 116 and 121 are parallel tothe row direction (the extension direction of the common electrode 113).The color filter 122 is provided to separate the color of light havingpassed through the liquid crystal layer 130 to, for example, threeprimary colors of red (R), green (G), and blue (B), or four colors of R,G, B, and white (W).

[Touch Panel 20]

The touch panel 20 allows information to be entered by touching an imagedisplay face 1A (the surface of the touch panel 20) of the liquidcrystal display device 1 with an object (i.e., an external proximityobject). The object can be a finger, a pen, or other suitable memberwhich is in contact with or in close to the image display face 1A, forexample. The touch panel 20 is provided separately from the liquidcrystal display panel 10 and, for example, is attached to the surface ofthe liquid crystal display panel 10 via an adhesive (not shown) or thelike. The touch panel 20 corresponds to an illustrative example of theabove-described touch sensor of the electrostatic capacitance type, anddetects the contact or non-contact state by XY (row/column) matrix.

FIG. 7 illustrates an example of the top face configuration of the touchpanel 20. FIG. 8 illustrates an example of a sectional configurationtaken along line A-A of the touch panel 20 in FIG. 7. For example, asshown in FIGS. 7 and 8, the touch panel 20 has a scan-side substrate 210and a detection-side substrate 220 which are disposed opposing to eachother via an adhesion layer 23.

The scan-side substrate 210 is a transparent substrate disposed on theside (the side of the liquid crystal display panel 10) on which lightfrom the liquid crystal display panel 10 is incident in the touch panel20. The scan-side substrate 210 has, for example, in order form the sideof the liquid crystal display panel 10, a transparent substrate 21 and aplurality of scan electrodes 22. On the other hand, the detection-sidesubstrate 220 is a transparent substrate disposed on the side (theobserver side) from which light having passed through the touch panel 20goes out. The detection-side substrate 220 has, for example, in orderfrom the side of the liquid crystal display panel 10, a transparentsubstrate 24, a plurality of detection electrodes 25 (first detectionelectrodes), and a plurality of detection electrodes 26 (seconddetection electrodes).

In the touch panel 20, for example, a capacitive element is structuredby an adhesion layer 23, the transparent substrate 24, and the scanelectrode 22 and the detection electrode 25 which are disposed opposingto each other via the adhesion layer 23 and the transparent substrate24. The capacitive element functions as the touch sensor of theelectrostatic capacitance type in the touch panel 20. In the touch panel20, the detection electrodes 25 and 26 may be formed on the top face(the surface of the touch panel 20) of the transparent substrate 24, orthe under face of the transparent substrate 24. In the case where thedetection electrodes 25 and 26 are formed on the under face of thetransparent substrate 24, the capacitive element is structured by theadhesion layer 23, and the scan electrode 22 and the detectionelectrodes 25 and 26 disposed opposing to one another via the adhesionlayer 23.

The transparent substrates 21 and 24 are substrates transparent tovisible light, which can be, for example, light-transmission resinfilms. The scan electrode 22 and the detection electrodes 25 and 26 aremade of a material transparent to visible light, which can be, forexample, ITO.

The scan electrode 22 corresponds to one of electrodes of theelectrostatic capacitance type touch sensor, and is electricallyconnected to a scan line WSL2 (refer to FIG. 4). The scan electrode 22is formed, for example, in contact with the surface of the transparentsubstrate 21. The plurality of scan electrodes 22 have, for example, aband-like shape extending in a row direction (first direction) and aredisposed in parallel with each other. Each of the scan electrodes 22extends, for example, in a direction parallel with the common electrode113 in the liquid crystal display panel 10. At one end of each scanelectrode 22, the connection pad 22A to be connected to the peripheralcircuit 40 is formed.

The detection electrode 25 corresponds to the other electrode of thetouch sensor of the electrostatic capacitance type, and is electricallyconnected to a detection line DET (refer to FIG. 4). The detectionelectrode 25 is, for example, formed in contact with the surface of thetransparent substrate 24. The plurality of detection electrodes 25 havea band-shape electrode part extending in a direction (for example,column direction) (second direction) crossing the extending direction ofthe scan electrodes 22, and are disposed parallel with each other. Theelectrode part of the detection electrodes 25 faces any of the scanelectrodes 22. As shown in FIG. 7, the detection electrode 25 has aplurality of projection parts 25B coupled to the electrode part. Theprojection parts 25B are disposed in, for example, a region facing thescan electrodes 22. The projection part 25B protrudes in a direction(for example, the row direction) crossing the extension direction of theelectrode part and has, for example, a rod-like shape as shown in FIG.7. The detection electrode 25 has, for example, a comb-like shape formedby the electrode part, and the plurality of projection parts 25B. Theprojection part 25B does not always have to have the rod-like shape butmay have, for example, as shown in FIG. 9, an annular shape. Also, threeprojection parts 25B may be provided in each region facing the scanelectrode 22 as shown in FIG. 7, or two projection parts 25B may beprovided in each region facing the scan electrode 22 as shown in FIG.10. At one end of each detection electrode 25, a connection pad 25A tobe connected to the peripheral circuit 40 is formed. Preferably, theconnection pads 25A are disposed near one common side in the surface ofthe transparent substrate 24. Where appropriate, the connection pads 25Amay be disposed dispersedly near a plurality of sides of the surface ofthe transparent substrate 24.

The detection electrode 26 also corresponds to the other electrode inthe capacitive element, and is electrically connected to a detectionline DET (refer to FIG. 4). The detection electrode 26 is formed in thesame plane as that of the detection electrode 25, and is formed incontact with, for example, the surface of the transparent substrate 24.The plurality of detection electrodes 26 have a band-like shapeextending in a direction (for example, the column direction) crossingthe extension direction of the scan electrode 22, and are arranged inparallel with each other. The detection electrode 26 faces any of thescan electrodes 22. The detection electrode 26 is not provided with astructure similar to that of the projections 25B. Therefore, thedetection electrode 26 has a shape different from that of the detectionelectrode 25. At one end of each detection electrode 26, a connectionpad 26A to be connected to the peripheral circuit 40 is formed.Preferably, the connection pads 26A are disposed close to one commonside in the surface of the transparent substrate 24 together with theconnection pads 25A. Where appropriate, the connection pads 26A may bedisposed dispersedly near a plurality of sides of the surface of thetransparent substrate 24.

A line width of the detection electrode 25 is narrower than that of thedetection electrode 26 in each of the electrode part and the projectionpart 25B. In the detection electrode 25, the electrode part has a linewidth of, for example, about 100 μm, and the projection part 25B has aline width of, for example, about 10 μm. On the other hand, a line widthof the detection electrode 26 is wider than that of the detectionelectrode 25, and has, for example, a line width of about 500 μm.

The detection electrodes 25 and 26 are disposed so that at least onedetection electrode 25 and one detection electrode 26 are provided justbelow a contact part between the object such as the finger or the penand the image display face 1A (for example, a part surrounded by abroken-line circle in FIG. 7) when the object touches the image displayface 1A. That is, the detection electrodes 25 and 26 are disposed sothat the gap between the neighboring detection electrodes 25 and 26becomes smaller than the diameter of the contact part. Further, thedetection electrodes 25 and 26 are formed so that, for example, when theimage display surface 1A is touched with the object such as the fingeror the pen, a capacitance (capacitance C) formed between the detectionelectrode 25 and the object and a capacitance (capacitance D) formedbetween the detection electrode 26 and the object are almost equal toeach other. To make the detection electrodes 25 and 26 easily satisfysuch a condition, for example, as illustrated in FIGS. 7, 9, and 10,preferably, the detection electrodes 25 and 26 are disposed alternatelyin the row direction. Also, for example, as illustrated in FIGS. 7, 9,and 10, preferably, the projection parts 25B of the detection electrode25 are disposed closer to the adjacent detection electrode 26 ascompared with the electrode parts of the detection electrode 25.Further, for example, as illustrated in FIGS. 7, 9, and 10, preferably,the area of a part facing one scan electrode 22, of the detectionelectrode 25 and the area of a part facing one scan electrode 22, of thedetection electrode 26 are equalized to each other.

[Backlight 30]

The backlight 30 illuminates the back of the liquid crystal displaypanel 10, and has, for example, a light guide plate, a light sourcedisposed on a side face of the light guide plate, and an optical elementdisposed on the top face (light outgoing face) of the light guide plate.The light guide plate guides light from the light source to the top faceof the light guide plate, and, for example, has a shape formed in apredetermined pattern in one of the top face and the under face, and hasthe function of scattering light incident from the side face so as touniform the light. The light source is a linear light source, and ismade by, for example, an HCFL (Hot Cathode Fluorescent Lamp), CCFL, or aplurality of LEDs disposed linearly. The optical element is structuredby, for example, stacking a diffuser, a diffusion sheet, a lens film, apolarization separation sheet, or the like.

[Peripheral Circuit 40]

Next, circuits in the peripheral circuit 40 will be described withreference to FIG. 4. The peripheral circuit 40 drives the liquid crystaldisplay panel 10 and the touch panel 20, and detects an output of theabove-described touch sensor of the electrostatic capacitance type, forexample. The peripheral circuit 40 is, for example, mounted on thelight-incidence-side substrate 110 in the liquid crystal display panel10, or connected to a flexible print circuit board (FPC) connected tothe liquid crystal display panel 10 and the touch panel 20, for example.The peripheral circuit 40 has, for example, a video signal processcircuit 41 (first drive section), a timing generation circuit 42, asignal line drive circuit 43, a scan line drive circuit 44, a scan linedrive circuit 45 (second drive section), and a detection circuit 46(detection section).

The video signal process circuit 41 corrects, for example, the digitalvideo signal 40A which is input from the outside, converts the correctedvideo signal to an analog signal, and outputs the analog signal to thesignal line drive circuit 43. The timing generation circuit 42 controls,for example, so that the signal line drive circuit 43 and the scan linedrive circuits 44 and 45 operate in conjunction with one another. Thetiming generation circuit 42 outputs, for example, a control signal 42Ato those circuits according to (synchronously with) a sync signal 40Bwhich is input from the outside.

The signal line drive circuit 43 applies an analog video signal (asignal potential corresponding to the video signal 40A) input from thevideo signal process circuit 41 to signal lines DTL to write the analogvideo signal to the selected pixels 11. The signal line drive circuit43, for example, outputs a signal potential corresponding to the videosignal 40A. The signal line drive circuit 43, for example, performsframe inversion driving of writing a signal to the selected pixels 11,by applying a signal potential, which inverts every frame period withrespect to reference potential, to each of the signal lines DTL. Theframe inversion driving is performed to suppress deterioration in theliquid crystal element 12, and is used where appropriate. Further, thesignal line drive circuit 43, for example, also performs 1H inversiondrive of writing a signal to the selected pixels 11, by applying asignal potential, which inverts every 1H period with respect to thereference potential, to each of the signal lines DTL. The 1H inversiondriving is performed to suppress occurrence of flicker in each frame dueto inversion of the polarity of a voltage applied to the liquid crystalelement 12, and is used where appropriate. Here, the reference potentialis a potential of the common connection line COM, and is, for example, aground potential.

The scan line drive circuit 44 sequentially applies a selection pulse toa plurality of scan lines WSL1 according to (synchronously with) inputof the control signal 42A to select a plurality of pixels 11 by desiredunit. As the unit of selecting the pixels 11, for example, as neededbasis, various units may be selected such as one line or neighboring twolines. The selection of the pixels 11 may be, for example, sequentialselection or random selection. The scan line drive circuit 44 outputs,for example, a voltage applied to turn on the transistor 13 and avoltage applied to turn off the transistor 13.

The scan line drive circuit 45 sequentially applies a selection pulse toa plurality of scan lines WSL2 according to (synchronously with) inputof the control signal 42A to select a plurality of scan electrodes 22 bydesired unit. As the unit of selecting the scan electrodes 22, forexample, as needed basis, various units may be selected such as one lineor neighboring two lines. The selection of the scan electrodes 22 maybe, for example, sequential selection or random selection.

The scan line drive circuit 45 has, for example, as illustrated in FIG.11, a switching element 45A connected to one end of the scan line WSL2.The other end of the scan line WSL2 is electrically connected to thescan electrode 22 (the connection pad 22A). One switching element 45A isprovided for each scan line WSL2, and has, for example, two inputterminals. One input terminal of the switching element 45A is, forexample, connected to an AC signal source 45B via a line L₁. The ACsignal source 45B outputs an AC rectangular wave Sg of a predeterminedfrequency (for example, a few kHz to tens kHz). The other input terminalof the switching element 45A is connected to, for example, a logiccircuit 45C via a line L₂. The logic circuit 45C outputs, for example, apredetermined fixed potential (for example, a potential in the range of0V to 5V). The AC signal source 45B and the logic circuit 45C are, forexample, connected to the reference potential line 108 or the like asillustrated in FIG. 11. The reference potential line 108 is, forexample, a line connected to the member which applies the potential asthe reference of the circuit operation in the liquid crystal displaydevice 1. The scan line drive circuit 45 may be constructed by circuitsdifferent from those illustrated in FIG. 11.

Next, the detection circuit 46 will be described. The detection circuit46 detects the contact position of the object such as a finger, on thebasis of a detection signals V_(det) obtained from the plurality ofdetection electrodes 25 and 26. More specifically, the detection circuit46 detects whether the object such as the finger is in contact with theimage display face 1A or not, on the basis of the difference between thedetection signal V_(det) obtained from the detection electrode 25 andthe detection signal V_(det) obtained from the detection electrode 26.When the difference is equal to or less than the predetermined thresholdvoltage Vth, the detection circuit 46 determines that the object is incontact with the image display face 1A. When the difference exceeds thepredetermined threshold voltage Vth, the detection circuit 46 determinesthat the object is not in contact with the image display face 1A. Whenit is detected that the object such as the finger is in contact with theimage display face 1A, the detection circuit 46 executes the followingprocess. Specifically, the detection circuit 46 calculates the positionof contact of the object such as the finger in the image display face1A, on the basis of the timing of applying the selection pulse outputfrom the scan line drive circuit 45 and the timing of detecting thedifference which is equal to or less than the threshold voltage V_(th).

The detection circuit 46 has, for example, as shown in FIG. 12, adifferential circuit 50 at an input stage. The detection circuit 46 has,for example, at the post stage of the difference circuit 50, anoperational amplifier 51 for amplifying a signal, a low pass filter(LPF) 52, a high pass filter (HPF) 53, a rectifying and smoothing unit54, and a comparator 55. Two input terminals T_(in1) and T_(in2) of thedifference circuit 50 are electrically connected to the detectionelectrodes 25 and 26 (the connection pads 25A and 26A). Therefore, tothe input terminals T_(in1) and T_(in2), the detection signal V_(det)output from the detection electrode 25 and the detection signal V_(det)output from the detection electrode 26 are input. The positive inputterminal (+) of the operational amplifier 51 is connected to the outputterminal of the difference circuit 50, and the output terminal of theoperational amplifier 51 is connected to the rectifying and smoothingunit 54 via the LPF 52. To the LPF 52, the HPF 53 is connected. The LPF52 has a configuration that, for example, a resistor 52R and a capacitor52C are connected in parallel. The HPF 53 has a configuration that, forexample, a resistor 53R and a capacitor 53C are connected in series inthe reference potential line 108. The connection point between the LPF52 and the HPF 53 is connected to the negative input terminal (−) of theoperational amplifier 51. The rectifying and smoothing unit 54 has, forexample, a rectifying unit configured of a half-wave rectifier diode54D, and a smoothing unit obtained by connecting a resistor 54R and thecapacitor 52C in parallel in the reference potential line 108. Theoutput terminal of the rectifying and smoothing unit 54 is connected tothe positive input terminal (+) of the comparator 55. The predeterminedthreshold voltage V_(th) is input to the negative input terminal (−) ofthe comparator 55. The output terminal of the comparator 55 is connectedto the output terminal T_(out), and the output terminal T_(out) isconnected to a not-shown computing circuit. Therefore, on the basis of adetection result (contact or non-contact) output from the outputterminal T_(out), a predetermined information process is performed bythe computing circuit.

The detection circuit 46 having such a configuration operates asfollows. The difference between the two detection signals V_(det) inputto the input terminals T_(in1) and T_(in2) is calculated by thedifference circuit 50, and a signal (differential signal) obtained bythe calculation is amplified by the operational amplifier 51. Afterthat, low frequency components of the signal pass through the LPF 52,and high frequency components are removed by the HPF 53. The ACcomponents of low frequency having passed through the LPF 52 aresubjected to half-wave rectification by the diode 54D of the rectifyingand smoothing unit 54. After that, the resultant becomes a smoothedlevel signal, and the level signal is input to the comparator 55. In thecomparator 55, the input level signal is compared with the thresholdvoltage V_(th). When the level signal is equal to or less than thethreshold voltage V_(th), a touch detection signal is output from thecomparator 55. When the touch detection signal is input to the computingcircuit, in the computing circuit, the touch position is calculated onthe basis of the application timing of the selection pulse and thedetection timing of the detection signal V_(det) which is equal to orless than the threshold voltage V_(th). Incidentally, the detectioncircuit 46 may be structured by circuits different from those shown inFIG. 12.

[Operation]

An example of the operation of the liquid crystal display device 1according to the present embodiment will now be described.

In the liquid crystal display device 1, the signal potentialcorresponding to the video signal 40A is applied to the signal lines DTLby the signal line drive circuit 43, and the selection pulse accordingto the control signal 42A is sequentially applied to the plurality ofscan lines WSL1 by the scan line drive circuit 44. Consequently, atransverse electric field having a magnitude corresponding to the signalpotential is applied on the pixel 11 unit basis to the liquid crystallayer 130, and the liquid crystal molecules are aligned in apredetermined direction. Therefore, the light from the backlight 30 ismodulated on the pixel 11 unit basis in the liquid crystal layer 130 inaccordance with the alignment direction of the liquid crystal molecules.As a result, an image is displayed on the image display face 1A.

In the liquid crystal display device 1, further, the selection pulse issequentially applied to the plurality of scan lines WSL2 by the scanline drive circuit 45. Thus, capacitive elements (corresponding to thecapacitive elements 104) each formed in the intersection part of thescan electrode 22 and the detection electrode 25 are sequentiallychanged/discharged, and the detection signal V_(det) of the level basedon the capacitance value of the capacitive element is output from eachof the plurality of detection electrodes 25. The outputs (detectionsignals V_(det)) from the plurality of detection electrodes 25 are inputto the detection circuit 46. In a state where a finger of the user isnot in contact with the surface of the touch panel 20, the level of thedetection signal V_(det) is almost constant.

When a finger of the user touches any place in the surface of the touchpanel 20, a capacitive element formed by the finger or the like (thecapacitive element corresponding to the capacitive element 109) is addedto the capacitive element formed in the position where the finger or thelike is touched. Consequently, the difference of the two detectionsignals V_(det) output from the detection electrodes 25 and 26 when theselection pulse is applied to the scan electrode 22 corresponding to thetouch position becomes smaller than the difference of the two detectionsignals V_(det) output from the electrodes 25 and 26 when the selectionpulse is applied to another place. In the detection circuit 46, thatdifference is compared with the threshold voltage V_(th). For example,when the difference is equal to or less than the threshold voltageV_(th), it is determined that the finger or the like is in contact withthe surface of the touch panel 20. The contact position is determinedfrom the application timing of the selection pulse and the detectiontiming of the detection signal V_(det) which is equal to or less thanthe threshold voltage V_(th) in the detection circuit 46.

[Operation and Effects]

Next, the operation and effects of the liquid crystal display device 1according to the present embodiment will be described.

Generally, in a detection method of the electrostatic capacitance type,due to the principle of the method, when a finger or the like of theuser touches the surface of the touch panel, the capacitive elementformed by the finger or the like has to be added to the detectionelectrode provided in the touch panel. Thus, the detection electrode isprovided on or near the surface of the touch panel, although externalnoise thereby easily enters the detection electrode. In particular, whenthe touch panel is used for a mobile device, the user holding the mobiledevice by his/her hand becomes an antenna and receives external noise,and the received noise enters the detection electrode via the hand ofthe user. When the noise enters the detection electrode, an output ofthe detection electrode (the value of the detection signal) fluctuates.Thus, contact/non-contact may be erroneously determined.

However, in the present embodiment, the two kinds of the detectionelectrodes 25 and 26 having different line widths are provided for thetouch panel 20, as one of the electrodes of the touch sensor of theelectrostatic capacitance type used for detecting thecontact/non-contact state. The detection electrodes 25 and 26 aredisposed opposing to the scan electrode 22 via the predetermined gap.Thus, when voltage is applied between the scan electrode 22 and thedetection electrodes 25 and 26, for example, lines of electric force asillustrated in FIG. 13 are generated between the scan electrode 22 andthe detection electrodes 25 and 26. In the gap between the scanelectrode 22 and the detection electrodes 25 and 26, the lines ofelectric force extend almost straight. By the electric fields generatedin the gap, a parallel plate capacitance C₁ is formed. On the otherhand, around the gap between the scan electrode 22 and the detectionelectrodes 25 and 26, the lines of electric force extend largely aroundthe top face side of the detection electrodes 25 and 26, and extend tothe observer side more than the image display face 1A with which afinger or the like comes in contact. By the round electric field, afringe capacitance C₂ is formed.

Although the parallel plate capacitance C₁ and the fringe capacitance C₂are formed for both of the detection electrodes 25 and 26 as describedabove, a region in which the parallel plate capacitance C₁ is formed inthe detection electrode 25 having the narrower line width is smallerthan that of the detection electrode 26 having the wider line width.That is, a value of the parallel plate capacitance C₁ in the detectionelectrode 25 is smaller than that in the detection electrode 26. On theother hand, a size of a region in which the fringe capacitance C₂ isformed largely does not have the relation with the line width, and isproportional to the length of an edge of the detection electrodes 25 and26. For example, as shown in FIGS. 7, 9, and 10, since the detectionelectrode 25 is provided with the projections 25B, the edge of thedetection electrode 25 is longer than that of the detection electrode 26by the amount of the length of the edge included in the projection part25B. Consequently, the region in which the fringe capacitance C₂ isformed in the detection electrode 25 is wider than that of the detectionelectrode 26 by the amount of the length of the edge included in theprojection part 25B. Therefore, a rate of the fringe capacitance C₂ inthe capacitance (total capacitance) obtained by adding the parallelplate capacitance C₁ and the fringe capacitance C₂ in the detectionelectrode 25 is larger than that in the detection electrode 26.

It is now assumed that a finger or the like is brought close to thedetection electrodes 25 and 26 and interrupts the electric field formingthe fringe capacitance C₂. Due to the interruption with the finger orthe like, the fringe capacitance C₂ decreases, and, in associationtherewith, the total capacitance also decreases. A fluctuation rate(decrease rate) of the total capacitance in the detection electrode 25is higher than that of the detection electrode 26. Therefore, when theplurality of scan electrodes 22 are selected in desired unit, the signallevel of the detection signal V_(det) obtained from the detectionelectrode 25 fluctuates largely between the time when the finger or thelike touches the image display face 1A and the time when the finger orthe like does not touch the image display face 1A. On the other hand,the signal level of the detection signal V_(det) obtained from thedetection electrode 26 fluctuates only by a fluctuation amount smallerthan the fluctuation amount in the detection electrode 25, between thetime when the finger or the like touches the image display face 1A andthe time when the finger or the like does not touch the image displayface 1A.

As described above, in the present embodiment, the sensitivity to touchof a finger or the like in the detection electrode 25 is higher thanthat in the detection electrode 26. Further, the sensitivity to touch ofa finger or the like in the detection electrode 25 is almost constantregardless of the scan electrode 22. Similarly, the sensitivity to touchof a finger or the like in the detection electrode 26 is almost constantregardless of the scan electrode 22. In other words, in the presentembodiment, the detection electrodes 25 and 26 having differentsensitivities to touch of a finger or the like are provided for thetouch panel 20.

Also, in the present embodiment, the detection electrodes 25 and 26 areformed so that, for example, when the object such as a finger or pentouches the image display face 1A, the capacitance (capacitance C)formed between the detection electrode 25 and the object, and thecapacitance (capacitance D) formed between the detection electrode 26and the object, are almost equalized. In the present embodiment, forexample, as shown in FIGS. 7, 9, and 10, in the case where the detectionelectrodes 25 and 26 are disposed alternately in the row direction, ordisposed so that the projections 25B of the detection electrode 25 arecloser to the neighboring detection electrode 26 more than the electrodeparts of the detection electrode 25, the capacitance C and thecapacitance D are almost equalized. In the present embodiment, forexample, as shown in FIGS. 7, 9, and 10, also in the case where the areaof the part facing one scan electrode 22 in the detection electrode 25and the area of the part facing one scan electrode 22 in the detectionelectrode 26 are equalized, the capacitance C and the capacitance D arealmost equalized.

Consequently, for example, sensitivity to external noise in thedetection electrode 25 and that in the detection electrode 26 are almostequalized when the user becoming as an antenna and catching the externalnoise touches the panel with his/her finger and the external noise istransmitted to the touch panel 20 via the finger. In the case where thesensitivity to the external noise of the detection electrode 25 and thesensitivity to the external noise of the detection electrode 26 areequal to each other, the signal level of the external noise included inthe detection signal V_(det) obtained from the detection electrode 25and that of the external noise included in the detection signal V_(det)obtained from the detection electrode 26 are equal to each other.Therefore, for example, by calculating the difference between thedetection signal V_(det) obtained from the detection electrode 25 andthat obtained from the detection electrode 26, the external noise iseliminated from the detection signals.

Part (A) to Part (H) of FIG. 14 illustrate an example of signalwaveforms when the detection electrodes 25 and 26 have the configurationas illustrated in FIG. 7, 9, or 10 and when, in a state the touch panel20 is touched with a finger, the plurality of scan lines WSL2 aresequentially driven. In Parts (A) to (D) of FIG. 14, the number at theend of each of WSL2(1), WSL2(2), WSL2(3), and WSL2(4) indicates serialnumber (sequence number) of the scan line WSL2. The number at the end ofeach of DET(1) and DET(2) in Parts (F) and (G) of FIG. 14 indicatesserial number (sequence number) of the detection lines DET. In Parts (F)to (H) of FIG. 14, DET(1) corresponds to the detection line DETconnected to the detection electrode 25, and DET(2) corresponds to thedetection line DET connected to the detection electrode 26. Parts (F) to(H) of FIG. 14 illustrate signal waveforms obtained when a fingertouches a region opposing the crossing part of the first to third scanlines WSL2 and the first and second detection lines DET.

It can be seen from Parts (F) and (G) of FIG. 14, that when the first tothird scan lines WSL2 are selected, the detection signal V_(det) of thevoltage Va is obtained from the first selection line DET, and thedetection signal V_(det) of a voltage Vb (>Va) is obtained from thesecond selection line DET. The reason why the signal level of thedetection signal V_(det) varies between the first selection line DET andthe second selection line DET is that the sensitivity to touch with afinger or the like in the detection electrode 25 connected to the firstselection line DET is higher than that in the detection electrode 26connected to the second selection line DET.

It can also be seen from Parts (F) and (G) of FIG. 14 that, when thefourth scan line WSL2 is selected, the detection signal V_(det) of thevoltage Vc is obtained from the selection line DET(1), and the detectionsignal V_(det) of a voltage Vd (=Vc) is obtained from the selection lineDET. The reason why the signal level of the detection signal V_(det) ofthe first selection line DET and that of the second selection line DETare the same is that a finger does not touch a part just above thefourth scan line WSL2 and the detection electrodes 25 and 26 are hardlyinfluenced by the finger.

It can also be seen from Parts (E) to (G) of FIG. 14 that noise havingthe same phase as that of external noise is included at almost the samelevel in the detection signal V_(det) obtained from the first selectionline DET and the detection signal V_(det) obtained from the secondselection line DET. The reason is that the sensitivity to the externalnoise in the detection electrode 25 connected to the first selectionline DET and that in the detection electrode 26 connected to the secondselection line DET are almost equal to each other.

It can be seen from Part (H) of FIG. 14 that, by obtaining thedifference between the detection signal V_(det) obtained from DET(1) andthe detection signal V_(det) obtained from DET(2), a fluctuationcomponent (Vb−Va) of the detection signal V_(det) by touch of a fingeris extracted. It can also be seen from Part (H) of FIG. 14 that noisehaving the same phase as that of the external noise is eliminated fromthe detection signal V_(det).

From the above, by providing the two kinds of the detection electrodes25 and 26 having the different sensitivities to the contact/non-contactstate and having the almost equal sensitivities to the external noise,the external noise is eliminated from the detection signal V_(det) onlyby calculating the difference of the detection signals V_(det).Therefore, it is possible to eliminate the erroneous detection caused bythe external noise.

Modification of First Embodiment [Modification 1]

Although the case where one scan electrode 22 is connected to one scanline WSL2 has been described in the foregoing embodiment, the pluralityof neighboring scan electrodes 22 may be connected to one scan lineWSL2. In such a case, as compared with the case where one scan electrode22 is connected to one scan line WSL2, the signal level of the detectionsignal V_(det) obtained from the detection electrodes 25 and 26 becomeshigher. Incidentally, only by simply increasing the line width of thescan electrode 22 and the detection electrodes 25 and 26, the signallevel of the detection signal V_(det) is made higher. However, in such acase, as described above, when the line width is increased, only theparallel plate capacitance C₁ increases, and the capacitance C and thecapacitance D decrease. Therefore, the sensitivity to touch with afinger or the like decreases. On the other hand, as in the presentmodification, in the case of connecting the plurality of neighboringscan electrodes 22 to one scan line WSL2, not only the parallel platecapacitance C₁ but also the fringe capacitance C₂ increase, and thecapacitance C and the capacitance D do not change. Thus, there is nopossibility that the sensitivity to touch with a finger or the likedecreases.

[Modification 2]

In the foregoing embodiment, the detection electrodes 25 and 26 areformed so that the capacitances C and D become almost equal to eachother. However, for example, due to manufacture error or the like, theremay be a case that the capacitances C and D are slightly different fromeach other. For example, in the case where the projection parts 25B ofthe detection electrode 25 are eliminated and the detection electrode 25is formed in a rod-like shape as illustrated in FIG. 15, thecapacitances C and D are largely different from each other. In the casewhere there is a difference between the capacitances C and D, the signallevel of the external noise included in the detection signal V_(det)obtained from the detection electrode 25 and that of the external noiseincluded in the detection signal V_(det) obtained from the detectionelectrode 26 become different from each other. Consequently, even if thedifference between the detection signal V_(det) obtained from thedetection electrode 25 and the detection signal V_(det) obtained fromthe detection electrode 26 is simply obtained, the external noise is noteliminated from the detection signal V_(det). Therefore, in the presentmodification, the case where there is a difference between the signallevels of external noises included in the detection signals V_(det) isassumed, and means for correcting the difference is also provided.

For example, in the present modification, as illustrated in FIG. 16, inthe detection circuit 46, an output adjustment circuit 56 is providedbetween the difference circuit 50 and the input terminals T_(in1) andT_(in2). The output adjustment circuit 56 makes the signal level of thedetection signal V_(det) input to the input terminal T_(in1) and thesignal level of the detection signal V_(det) input to the input terminalT_(in2) equal to each other. Incidentally, it is assumed here that thedetection electrode 25 is connected to the input terminal T_(in1) andthe detection electrode 26 is connected to the input terminal T_(in2).

[Example of Using Operational Amplifier Whose Magnification isAdjustable]

The output adjustment circuit 56 has, for example, two operationalamplifiers 56A and 56B. The positive input terminal (+) of theoperational amplifier 56A is connected to the input terminal T_(in1),and the output terminal of the operational amplifier 56A is connected toone of input terminals of the difference circuit 50. The negative inputterminal (−) of the operational amplifier 56A is connected to the outputterminal of the operational amplifier 56A, and the operational amplifier56A serves as a voltage follower. The positive input terminal (+) of theother operational amplifier 56B is connected to the input terminalT_(in2), and the output terminal of the operational amplifier 56B isconnected to the other input terminal of the difference circuit 50. Thenegative input terminal (−) of the operational amplifier 56B isconnected to one end of each of a variable resistor 56C and a fixedresistor 56D which are connected in series, and the other end of each ofthe variable resistor 56C and the fixed resistor 56D which are connectedin series are connected to the reference potential line 108. Aconnection point between the variable resistor 56C and the fixedresistor 56D is connected to the output terminal of the operationalamplifier 56B. Therefore, the operation amplifier 56A is a non-inversionamplifier.

The variable resistor 56C in the output adjustment circuit 56 isadjusted, for example, as follows. First, a voltmeter is connected totwo outputs of the output adjustment circuit 56. Next, under environmentwhere there is no external noise, in a state where the image displayface 1A is touched with a conductor to which a voltage source isconnected (for example, a pseudo finger), a predetermined fixed voltageis applied to the scan line WSL2 just below the conductor. Thus, thedetection signals V_(det) output from the detection electrodes 25 and 26are input to the voltmeter via the output adjustment circuit 56, and thevoltage level of the input signal is displayed on the voltmeter. Next,the voltage of the conductor is set to a predetermined voltage value byusing a voltage source, and the value of the variable resistor 56C isadjusted while seeing display of the voltmeter so that the values of thedetection signals V_(det) obtained from the detection electrodes 25 and26 become equal to each other.

As described above, in the present modification, the signal level of thedetection signal V_(det) input to the input terminal T_(in2) iscorrected by using the variable resistor 56C whose resistance value isadjusted. After that, the difference between the corrected detectionsignal and the detection signal V_(det) input to the input terminalT_(in2) is obtained. Thereby, the external noise is eliminated from thedetection signal V_(det). Therefore, it is possible to eliminate theerroneous detection caused by the external noise. Incidentally, thecorrection on the signal level of the detection signal V_(det) may beperformed only on the detection signal V_(det) input to the inputterminal T_(in1), or may be performed on both of the detection signalsV_(det) input to the input terminals T_(in1) and T_(in2).

[Example of Using Arithmetic Circuit]

In the above-described modification, the output adjustment circuit 56 isstructured by an analog circuit including the operational amplifierwhose magnification is adjustable. The output adjustment circuit 56 maybe structured by a digital circuit such as a ROM (Read-Only Memory) onwhich a program for correcting noise level is written. The programwritten on the digital circuit includes a correction formula forcorrecting the noise level.

When the signal level of the detection signal V_(det) input to the inputterminal T_(in1) is V_(in1), and that of the detection signal V_(det)input to the input terminals T_(in2) is set to V_(in2), the correctionformula is expressed, for example, by the following formulae (1) and(2).

V _(c1) =α×V _(in1)   (1)

V_(c1)=V_(in2)   (2)

In the above formulae, only V_(in1) is corrected. However, for example,as shown in the following formulae (3) and (4), only V_(in2) may becorrected. Also, both of them may be corrected.

V_(c1)=V_(in1)   (3)

V _(c1)=(1/α)×V _(in2)   (4)

A correction factor a in the correction formulae for correcting thenoise level is set, for example, as follows. First, a voltmeter isconnected to the detection line DET connected to the detection electrode25 and the detection line DET connected to the detection electrode 26.Next, under environment where there is no external noise, in a statewhere the image display face 1A is touched with a conductor to which avoltage source is connected (for example, a pseudo finger), apredetermined fixed voltage is applied to the scan line WSL2 just belowthe conductor. Thus, the detection signals V_(det) output from thedetection electrodes 25 and 26 are input to the voltmeter, and thevoltage level of the input signal is displayed on the voltmeter. Next,the voltage of the conductor is set to a predetermined voltage value byusing a voltage source, and the indication in the voltmeter at that timeis read. After that, a ratio (Vy/(Vx−Vy)) between the voltage value Vxof the detection signal V_(det) output from the detection electrode 25and the voltage value Vy of the detection signal V_(det) output from thedetection electrode 26 is calculated. The ratio is set as the correctionfactor α.

As described above, in the present modification, the signal level of thedetection signal V_(det) input to the input terminal T_(in2) iscorrected by using the correction formula in which the value of thecorrection factor a is set. After that, the difference between thecorrected detection signal and the detection signal V_(det) input to theinput terminal T_(in2) is obtained. Thereby, the external noise iseliminated from the detection signal V_(det). Therefore, it is possibleto eliminate the erroneous detection caused by the external noise.Incidentally, the correction on the signal level of the detection signalV_(det) may be performed only on the detection signal V_(det) input tothe input terminal T_(in1), or may be performed on both of the detectionsignals V_(det) input to the input terminals T_(in1) and T_(in2).

Second Embodiment

FIG. 17 illustrates an example of the top face configuration of thetouch panel 20 included in a liquid crystal display device according toa second embodiment of the invention. The liquid crystal display deviceof the second embodiment is different from the liquid crystal displaydevice of the foregoing embodiment, in that a plurality of detectionelectrodes 27 are provided in place of the plurality of detectionelectrodes 25, and a plurality of detection electrodes 28 are providedin place of the plurality of detection electrodes 26 in the touch panel20. In the following, the points different from the configuration of theforegoing embodiment will be mainly described, and description of theconfiguration common to that of the foregoing embodiment will not berepeated. In the following, the same reference numerals are designatedto components common to those described above.

The detection electrode 27 corresponds to the other electrode in thetouch sensor of the electrostatic capacitance type, and is electricallyconnected to the detection line DET. The detection electrode 27 is, forexample, formed in contact with the surface of the transparent substrate24. The plurality of detection electrodes 27 have a band-shape electrodepart extending in a direction (for example, the column direction)crossing the extending direction of the scan electrodes 22, and aredisposed parallel with each other. The electrode part of the detectionelectrodes 27 faces any of the scan electrodes 22. As shown in FIG. 17,the detection electrode 27 has a plurality of projection parts 27Bcoupled to the electrode part. The projection parts 27B are disposed in,for example, a region facing the scan electrodes 22 among the pluralityof scan electrodes 22. The projection part 27B protrudes in a direction(for example, the row direction) crossing the extension direction of theelectrode part, and has, for example, a rod-like shape as shown in FIG.17. The detection electrode 27 has, for example, a comb-like shapeformed by the electrode part and the plurality of projection parts 27B.The projection part 27B does not always have to have the rod-like shape,but may have another shape. At one end of each detection electrode 27, aconnection pad 27A which is to be connected to the peripheral circuit 40is formed. Preferably, the connection pads 27A are disposed near onecommon side in the surface of the transparent substrate 24. Whereappropriate, the connection pads 27A may be disposed dispersedly near aplurality of sides of the surface of the transparent substrate 24.

The detection electrode 28 also corresponds to the other electrode inthe capacitive element, and is electrically connected to the detectionline DET. The detection electrode 28 is formed in the same plane as thatof the detection electrode 27, and is formed in contact with, forexample, the surface of the transparent substrate 24. The plurality ofdetection electrodes 28 have a band-like shape extending in a direction(for example, the column direction) crossing the extension direction ofthe scan electrode 22, and are arranged in parallel with each other. Thedetection electrode 28 faces any of the scan electrodes 22. Thedetection electrode 28 also has, as illustrated in FIG. 17, a pluralityof projections 28B coupled to the electrode part. The projections 28Bare disposed in regions facing the scan electrodes 22 which do not facethe projections 27B among the plurality of scan electrodes. That is, theprojections 27B and 28B are provided in the regions facing the differentscan electrodes 22. Therefore, the detection electrode 28 has a shapedifferent from that of the detection electrode 27. For example, in thecase where the projections 27B are provided in the regions facing theodd-numbered scan electrodes 22, the projections 28B are provided in theregions facing the even-numbered scan electrodes 22. For example, in thecase where the projections 27B are provided in the regions facing theeven-numbered scan electrodes 22, the projections 28B are provided inthe regions facing the odd-numbered scan electrodes 22.

The projection part 28B protrudes in a direction (for example, the rowdirection) crossing the extension direction of the electrode part, andhas, for example, a rod-like shape as shown in FIG. 17. The detectionelectrode 28 has, for example, a comb-like shape formed by the electrodepart and the plurality of projection parts 28B. In the detectionelectrode 28, for example, the projection parts 28B are disposed closeto the projection parts 27B so that the projection parts 27B of thedetection electrode 27 and the projection parts 28B of the detectionelectrode 28 are disposed alternately in a direction (for example, thecolumn direction) crossing the extension direction of the scanelectrodes 22. Preferably, the connection pads 28A are disposed near onecommon side in the surface of the transparent substrate 24 together withthe connection pads 27A. Where appropriate, the connection pads 28A maybe disposed dispersedly near a plurality of sides of the surface of thetransparent substrate 24.

The line width of the detection electrode 27 may be equal to ordifferent from that of the detection electrode 28. In the case where theline width of the detection electrode 27 is equal to that of thedetection electrode 28, a region in which the fringe capacitance C2 isformed in the detection electrode 27 becomes wider than that in thedetection electrode 28 by an amount of the length of the edge includedin the projection part 27B on the scan electrode 22 facing theprojection part 27B. In this case, when the scan electrode 22 facing theprojection part 27B is driven, the sensitivity to contact of a finger orthe like of the detection electrode 27 is higher than that of thedetection electrode 28. When the line width of the detection electrode27 is different from that of the detection electrode 28, the region inwhich the fringe capacitance C₂ is formed in any of the detectionelectrodes 27 and 28 becomes wider by an amount of the differencebetween the length of the edge in the detection electrode 27 included onthe scan electrode 22 facing the projection part 28B and the length ofthe edge in the detection electrode 28 included on the scan electrode 22facing the projection part 28B. In this case, when the scan electrode 22facing the projection part 28B is driven, the sensitivity to contact ofa finger or the like of the detection electrode 27 or 28 having thewider region in which the fringe capacitance C₂ is formed becomeshigher. That is, in the present embodiment, the sensitivity to contactof a finger or the like, of the detection electrodes 27 and 28 variesdepending on the scan electrode 22.

Also, in the present embodiment, the detection electrodes 27 and 28 aredisposed so that at least one detection electrode 27 and one detectionelectrode 28 are provided just below a contact part between the objectsuch as a finger or pen and the image display face 1A when the objecttouches the image display face 1A. That is, the detection electrodes 27and 28 are disposed so that the gap between the neighboring detectionelectrodes 27 and 28 becomes smaller than the diameter of the contactpart. Further, the detection electrodes 27 and 28 are formed so that,for example, when the image display surface 1A is touched with theobject such as a finger or pen, capacitance (capacitance C) formedbetween the detection electrode 27 and the object, and capacitance(capacitance D) formed between the detection electrode 28 and theobject, are almost equal to each other. In the present embodiment, forexample, when the detection electrodes 27 and 28 are disposedalternately in the row direction as shown in FIG. 17, the capacitances Cand D are almost equal to each other. Also, in the present embodiment,for example, when the projection parts 28B are disposed close to theprojection part 27B so that the projection parts 27B and 28B arealternatively disposed in a direction (for example, the columndirection) crossing the extension direction of the scan electrode 22 asillustrated in FIG. 17, the capacitances C and D are almost equal toeach other. Further, in the present embodiment, for example, as shown inFIG. 17, also in the case where the area of the part facing one scanelectrode 22 in the detection electrode 27 and that of the part facingone scan electrode 22 in the detection electrode 28 are equal to eachother, the capacitances C and D are substantially equal to each other.

Consequently, for example, the sensitivity to the external noise in thedetection electrode 27 and that in the detection electrode 28 is almostequalized when the user becoming as an antenna and catching the externalnoise touches the panel with his/her finger and the external noise istransmitted to the touch panel 20 via the finger. In the case where thesensitivity to the external noise of the detection electrode 27 and thesensitivity to the external noise of the detection electrode 28 areequal to each other, the signal level of the external noise included inthe detection signal V_(det) obtained from the detection electrode 27and that of the external noise included in the detection signal V_(det)obtained from the detection electrode 28 are equal to each other.Therefore, for example, by calculating the difference between thedetection signal V_(det) obtained from the detection electrode 27 andthat obtained from the detection electrode 28, it is possible toeliminate the external noise from the detection signals.

Part (A) to Part (H) of FIG. 18 illustrate an example of signalwaveforms when the detection electrodes 27 and 28 have the configurationillustrated in FIG. 17, and when, in a state where the touch panel 20 istouched with a finger, the plurality of scan lines WSL2 are sequentiallydriven. In Parts (A) to (D) of FIG. 18, the number at the end of each ofWSL2(1), WSL2(2), WSL2(3), and WSL2(4) indicates serial number (sequencenumber) of the scan line WSL2. The number at the end of each of DET(1)and DET(2) in Parts (F) and (G) of FIG. 18 indicates serial number(sequence number) of the detection lines DET. In Parts (F) to (H) ofFIG. 18, DET(1) corresponds to the detection line DET connected to thedetection electrode 27, and DET(2) corresponds to the detection line DETconnected to the detection electrode 28. Parts (F) to (H) of FIG. 18Fillustrate signal waveforms obtained when a finger touches the regionopposing the crossing part of the first and second third scan lines WSL2and the first and second detection lines DET.

It can be seen from Part (F) of FIG. 18 that, when the first scan lineWSL2 is selected, the detection signal V_(det) of the voltage Va isobtained from the first selection line DET, and the detection signalV_(det) of a voltage Vb (>Va) is obtained from the second selection lineDET. It can be seen from Part (G) of FIG. 18 that, when the second scanline WSL2 is selected, the detection signal V_(det) of the voltage Vb isobtained from the first selection line DET, and the detection signalV_(det) of the voltage Va is obtained from the second selection lineDET. The reason why the signal level of the detection signal V_(det)varies between the first selection line DET and the second selectionline DET is that the sensitivity to touch with a finger or the like inthe detection electrode 27 connected to the first selection line DET andthat in the detection electrode 28 connected to the second selectionline DET are different from each other.

It can also be seen from Parts (F) and (G) of FIG. 18 that, when thethird and fourth scan lines WSL2 are selected, the detection signalV_(det) of the voltage Vc is obtained from the selection line DET(1),and the detection signal V_(det) of a voltage Vd (=Vc) is obtained fromthe selection line DET(2). The reason why the signal level of thedetection signal V_(det) of the first selection line DET and that of thesecond selection line DET are the same is that a finger does not touchthe part just above the third and fourth scan lines WSL2, and thedetection electrodes 27 and 28 are hardly influenced by the finger.

It can also be seen from Parts (E) to (G) of FIG. 18 that noise havingthe same phase as that of the external noise is included at almost thesame level in the detection signal V_(det) obtained from the firstselection line DET and the detection signal V_(det) obtained from thesecond selection line DET. The reason is that the sensitivity to theexternal noise in the detection electrode 27 connected to the firstselection line DET and that in the detection electrode 28 connected tothe second selection line DET are almost equal to each other.

It can be seen from Part (H) of FIG. 18 that, by obtaining thedifference (the absolute value of the difference) between the detectionsignal V_(det) obtained from DET(1) and the detection signal V_(det)obtained from DET(2), a fluctuation component |Vb−Va| of the detectionsignal V_(det) by touch of a finger is extracted. It can also be seenfrom Part (H) of FIG. 18 that the noise having the same phase as that ofthe external noise is eliminated from the detection signal V_(det).

From the above, by providing the two kinds of the detection electrodes27 and 28 having the different sensitivities to the contact/non-contactstate and having the almost equal sensitivities to the external noise,the external noise is eliminated from the detection signal V_(det) onlyby calculating the difference of the detection signals V_(det).Therefore, it is possible to eliminate the erroneous detection caused bythe external noise.

Modification of Second Embodiment [Modification 1]

Although the case where one scan electrode 22 is connected to one scanline WSL2 has been described in the foregoing embodiment, the pluralityof neighboring scan electrodes 22 may be connected to one scan lineWSL2. In such a case, as compared with the case where one scan electrode22 is connected to one scan line WSL2, the signal level of the detectionsignal V_(det) obtained from the detection electrodes 27 and 28 is madehigher.

[Modification 2]

In the foregoing embodiment, the detection electrodes 27 and 28 areformed so that the capacitances C and D become almost equal to eachother. However, for example, due to manufacture error or the like, theremay be a case that the capacitances C and D are slightly different fromeach other. On the assumption of such a case, for example, the outputadjustment circuit 56 as shown in FIG. 16 may be further provided asmeans for ensuring that the erroneous detection caused by the externalnoise is eliminated. With this configuration, the external noise iseliminated from the detection signal V_(det) only by calculating thedifference between two signals output from the output adjustment circuit56. As a result, it is possible to eliminate the erroneous detectioncaused by the external noise.

Third Embodiment

FIG. 19 illustrates an example of the top face configuration of thetouch panel 20 included in a liquid crystal display device according toa third embodiment of the invention. The liquid crystal display deviceof the third embodiment is different from the liquid crystal displaydevice 1 of the foregoing embodiment, in that a plurality of detectionelectrodes 29 are provided in place of the plurality of detectionelectrodes 25 and 26, and a plurality of detection electrodes 31 areprovided in place of the plurality of detection electrodes 22 in thetouch panel 20. In the following, the points different from theconfiguration of the foregoing embodiment will be mainly described, anddescription of the configuration common to that of the foregoingembodiment will not be repeated.

In the present embodiment, as one of electrodes in the touch sensor ofthe electrostatic capacitance type, only one kind of the detectionelectrode 29 is provided. That is, different from the first and secondembodiments, the plurality of detection electrodes 29 having the sameshape are provided as one of electrodes in the touch sensor. Thedetection electrode 29 is formed, for example, in contact with thesurface of the transparent substrate 24, and is electrically connectedto the detection line DET. The plurality of detection electrodes 29 havea band-shape electrode part extending in a direction (for example, thecolumn direction) crossing the extending direction of the scanelectrodes 31 which will be described later, and are disposed parallelwith each other. The detection electrode 29 faces any of the scanelectrodes 31. The detection electrode 29 is not provided with thestructure which protrudes in the extending direction of the scanelectrode 31 which will be described later. The detection electrode 29has, for example, a rod-like shape. At one end of each detectionelectrode 29, a connection pad 29A which is to be connected to theperipheral circuit 40 is formed. Preferably, the connection pads 29A aredisposed near one common side in the surface of the transparentsubstrate 24. Where appropriate, the connection pads 29A may be disposeddispersedly near a plurality of sides of the surface of the transparentsubstrate 24. The line widths of the detection electrodes 29 are, forexample, equal to each other.

Also, in the present embodiment, the detection electrode 29 is disposedso that at least one detection electrode 29 is provided just below acontact part between an object such as a finger or pen and the imagedisplay face 1A when the object touches the image display face 1A. Thatis, the detection electrodes 29 are disposed so that the gap between theneighboring detection electrodes 29 becomes smaller than the diameter ofthe contact part. Further, the detection electrodes 29 are formed sothat, for example, when the image display surface 1A is touched with theobject such as a finger or pen, capacitances formed between thedetection electrodes 29 and the object are almost equal to each other.In the present embodiment, for example, when the detection electrodes 29have the same line width as shown in FIG. 19, the capacitances formedbetween the detection electrodes 29 and the object are almost equal toeach other.

The scan electrode 31 corresponds to the other electrode in theelectrostatic capacitance type touch sensor, and is electricallyconnected to the scan line WSL2. The scan electrode 31 is formed, forexample, in contact with the surface of the transparent substrate 21.The plurality of scan electrodes 31 have, for example, a band-shapedelectrode part extending in the row direction, and are disposed inparallel with each other. The electrode parts of the scan electrodes 31extend, for example, in a direction parallel with the common electrode113 in the liquid crystal display panel 10. At one end of each scanelectrode 31, the connection pad 31A to be connected to the peripheralcircuit 40 is formed.

For example, as illustrated in FIG. 19, the scan electrode 31 isprovided with a plurality of projection parts 31B. The projection parts31B are provided in a region facing the predetermined detectionelectrodes 29 among the plurality of detection electrodes 29, andprotrude in the extension direction of the detection electrodes 29. Forexample, the projection parts 31B are provided in the region facing theodd-numbered detection electrodes 29 among the plurality of detectionelectrodes 29 disposed in parallel, or provided in the region facing theeven-numbered detection electrodes 29 among the plurality of detectionelectrodes 29 disposed in parallel. That is, the projection parts 31B donot face the predetermined detection electrodes in the plurality ofdetection electrodes 29, and only the electrode parts of the scanelectrodes 31 face. The scan electrode 31 is thick in the portion wherethe projection part 31B is provided, and is narrow in the portion wherethe projection part 31B is not provided. That is, the shape of the scanelectrode 31 varies depending on the places (portions in the scanelectrode 31).

In the portion where the scan electrode 31 is thick, the edge includedin the part facing to overlap the scan electrode 31 in the detectionelectrode 29 is long. Consequently, in the detection electrode 29 facingthe projection part 31B in the plurality of detection electrodes 29, therate of the fringe capacitance C₂ in the total capacitance is high. Onthe other hand, in the narrow portion in the scan electrode 31, the edgeincluded in the portion facing to overlap the scan electrode 31 in thedetection electrode 29 is short. Therefore, in the detection electrode29 which does not face the projection part 31B in the plurality ofdetection electrodes 29, the rate of the fringe capacitance C₂ in thetotal capacitance is low.

As described above, in the present embodiment, the sensitivity to touchof a finger or the like in the detection electrode 29 facing theprojection part 31B in the plurality of detection electrodes 29 ishigher than that in the detection electrode 29 which does not face theprojection part 31B in the plurality of detection electrodes 29. Inother words, in the present embodiment, the detection electrodes 29having the mutually-different sensitivities to touch of a finger or thelike are provided for the touch panel 20.

Consequently, for example, when the user serves as an antenna andcatches external noise, and the user touches the panel with a finger andthe external noise is thus transmitted to the touch panel 20 via thefinger, the sensitivities to the external noise in the detectionelectrodes 29 are almost equalized. In the case where the sensitivitiesto the external noise in the detection electrodes 29 are equal to eachother, the signal levels of the external noises included in thedetection signals V_(det) obtained from the detection electrodes 29become equal to each other. Therefore, for example, by obtaining thedifference between the detection signal V_(det) obtained from thedetection electrode 29 facing the projection part 31B among theplurality of detection electrodes 29 and the detection signal V_(det)obtained from the detection electrode 29 which does not face theprojection part 31B among the plurality of detection electrodes 29, theexternal noise is eliminated from the detection signal.

From the above, in the present embodiment, by providing the two kinds ofthe detection electrodes 29 having the different sensitivities to thecontact/non-contact state and having the almost equal sensitivities tothe external noise, the external noise is eliminated from the detectionsignal V_(det) only by calculating the difference of the detectionsignals V_(det). Therefore, it is possible to eliminate the erroneousdetection caused by the external noise.

Fourth Embodiment

FIG. 20 illustrates an example of the top face configuration of thetouch panel 20 included in a liquid crystal display device according toa fourth embodiment of the invention. The liquid crystal display deviceof the fourth embodiment is different from the liquid crystal displaydevice of the third embodiment, in that a plurality of scan electrodes32 are provided in place of the plurality of detection electrodes 31 inthe touch panel 20 of the third embodiment. In the following, the pointsdifferent from the configuration of the foregoing embodiment will bemainly described, and description of the configuration common to that ofthe foregoing embodiment will not be repeated.

The scan electrode 32 corresponds to one of electrodes in the touchsensor of the electrostatic capacitance type, and is electricallyconnected to the scan line WSL2. The scan electrode 32 is formed, forexample, in contact with the surface of the transparent substrate 21.The plurality of scan electrodes 32 have, for example, a band-shapeelectrode part extending in the row direction, and are disposed parallelwith each other. The electrode parts of the scan electrodes 32 extend ina direction parallel with the common electrodes 113 in the liquidcrystal display panel 10. At one end of each scan electrode 32, aconnection pad 32A which is to be connected to the peripheral circuit 40is formed.

For example, as illustrated in FIG. 20, the scan electrode 32 isprovided with a plurality of projection parts 32B. The plurality ofprojection parts 32B are provided so as to sandwich regions facingpredetermined detection electrodes 29 among the plurality of detectionelectrodes 29 from the row direction, and extend in the extensiondirection of the detection electrodes 29. The projection parts 32B areprovided in a region facing the odd-numbered detection electrodes 29among the plurality of detection electrodes 29 disposed side-by-side, orin a region facing the even-numbered detection electrodes 29 among theplurality of detection electrodes 29 disposed side-by-side. That is, thedetection electrodes 29 do not face the projection parts 31B, but faceonly the electrode parts of the scan electrodes 32. The scan electrode32 is thick in the portion where the projection part 32B is provided,and is narrow in the portion where the projection part 32B is notprovided.

To the detection electrode 29 sandwiched by the projection parts 32Bamong the plurality of detection electrodes 29, as compared with thedetection electrode 29 which is not sandwiched by the projection parts32B among the plurality of detection electrodes 29, the larger number ofedges of the projection parts 32 are adjacent. Consequently, in thedetection electrode 29 sandwiched by the projection parts 32B among theplurality of detection electrodes 29, the rate of the fringe capacitanceC₂ in the total capacitance is high. On the other hand, in the detectionelectrode 29 which is not sandwiched by the projection parts 32B amongthe plurality of detection electrodes 29, the rate of the fringecapacitance C₂ in the total capacitance is low.

As described above, in the present embodiment, the sensitivity to touchof a finger or the like in the detection electrode 29 which issandwiched by the projection parts 32B among the plurality of detectionelectrodes 29 is higher than that in the detection electrode 29 which isnot sandwiched by the projection parts 32B among the plurality ofdetection electrodes 29. In other words, in the present embodiment, thedetection electrodes 29 having the mutually-different sensitivities totouch of a finger or the like are provided for the touch panel 20.

Consequently, for example, when the user serves as an antenna andcatches the external noise, and the user touches the panel with a fingerand the external noise is transmitted to the touch panel 20 via thefinger, the sensitivities to the external noise in the detectionelectrodes 29 are almost equalized. In the case where the sensitivitiesto the external noise in the detection electrodes 29 are equal to eachother, the signal levels of the external noises included in thedetection signals V_(det) obtained from the detection electrodes 29become equal to each other. Therefore, for example, by obtaining thedifference between the detection signal V_(det) obtained from thedetection electrode 29 sandwiched by the projection parts 32B among theplurality of detection electrodes 29 and the detection signal V_(det)obtained from the detection electrode 29 which is not sandwiched by theprojection parts 32B among the plurality of detection electrodes 29, theexternal noise is eliminated from the detection signals.

From the above, in the present embodiment, by providing the two kinds ofthe detection electrodes 29 having the different sensitivities to thecontact/non-contact state and having the almost equal sensitivities tothe external noise, the external noise is eliminated from the detectionsignal V_(det) only by calculating the difference of the detectionsignals V_(det). Therefore, it is possible to eliminate the erroneousdetection caused by the external noise.

Fifth Embodiment

Next, a liquid crystal display device 2 according to a fifth embodimentof the invention will be described. The liquid crystal display device 2according to the present embodiment is, as in the first embodiment, aliquid crystal display device with a touch sensor. The liquid crystaldisplay device 2 has, as a display element, a liquid crystal displayelement, and further includes a touch sensor of an electrostaticcapacitance type on the inside of the liquid crystal display element.That is, the liquid crystal display device 2 has a liquid crystaldisplay element of a touch sensor built-in type (in-cell type). Theliquid crystal display device 2 has, for example, as illustrated in FIG.21, a liquid crystal display panel 60, a backlight 30, and a peripheralcircuit 40.

[Liquid Crystal Display Panel 60]

The liquid crystal display panel 60 displays a video image bytransmitting or modulating light from the light source (backlight 30) bychanging arrangement of liquid crystal molecules. The liquid crystaldisplay panel 60 is, for example, a transmission-type display panel inwhich a plurality of pixels 11 disposed in matrix are driven inaccordance with the video signal 40A. As in the forgoing embodiments,for example, as shown in FIG. 5, the liquid crystal display panel 60 hasa plurality of scan lines WSL1 disposed as rows, and a plurality ofsignal lines DTL disposed as columns. The plurality of pixels 11 aredisposed in matrix in correspondence with intersections between the scanlines WSL1 and the signal lines DTL. In the liquid crystal display panel60, further, for example, a plurality of common connection lines COM aredisposed as rows. Each common connection line COM is disposed, forexample, for the pixels 11 in each row, and is connected to a scan linedrive circuit (common line drive circuit) 47 which will be describedlater.

The liquid crystal display panel 60 has, for example, as shown in FIG.22, a liquid crystal layer 130 (display function layer), and alight-incidence-side substrate 110 and a light-outgoing-side substrate120 which are disposed opposing to each other while sandwiching theliquid crystal layer 130. The light-incidence-side substrate 110 is atransparent substrate disposed on the incident side (backlight 30 side)of light from the backlight 30 in the liquid crystal display panel 60.The internal configuration of the light-incidence-side substrate 110 issimilar to that in the foregoing embodiments. On the other hand, thelight-outgoing-side substrate 140 is a transparent substrate disposed onthe outgoing side (observer side) of light modulated by the liquidcrystal layer 130 in the liquid crystal display panel 60. Thelight-outgoing-side substrate 120 has, for example, in order from theliquid crystal layer 130 side, an alignment film 121, a color filter122, a transparent substrate 123, an adhesion layer 125, detectionelectrodes 25 and 25, a transparent substrate 24, and a polarizer 124.

The color filter 122 may not be provided where appropriate. Also, asshown in FIG. 23, the transparent substrate 24 may not be provided whereappropriate. As shown in FIG. 24, a stacked body including, in orderfrom the side of the liquid crystal layer 130, the adhesive layer 125,the detection electrodes 25 and 26, and the transparent substrate 24 maybe provided on the top face (observer side) of the polarizer 124. In anyof the cases illustrated in FIGS. 22, 23, and 24, the detectionelectrodes 25 and 26 are not exposed from the top face of the liquidcrystal display panel 60.

For example, as shown in FIGS. 22, 23, and 24, the liquid crystaldisplay panel 60 has a common electrode 113 as one of electrodes of thetouch sensor of the electrostatic capacitance type, and does not havethe scan electrode 22 in the first embodiment. As in the firstembodiment, the liquid crystal display panel 60 has the detectionelectrode 25 as the other electrode of the touch sensor of theelectrostatic capacitance type. Further, for example, as illustrated inFIG. 22, the liquid crystal display panel 60 has, as a dielectric of thetouch sensor of the electrostatic capacitance type, an insulating layer114, an alignment film 116, the liquid crystal layer 130, the alignmentfilm 121, the color filter 122, the transparent substrate 123, and theadhesive layer 125. In the case where the liquid crystal display panel60 has, for example, the configuration illustrated in FIG. 24, thedielectric sandwiched by a pair of electrodes in the touch sensor of theelectrostatic capacitance type has a configuration obtained by addingthe polarizer 124 to the above-described configuration.

In the present embodiment, the common electrode 113 also serves as thescan electrode 22 of the foregoing embodiments, and is electricallyconnected to the common connection line COM. For example, the commonelectrode 113 is formed in contact with the surface of the transparentsubstrate 112. The plurality of common electrodes 113 have, for example,a band-like shape extending in the row direction, and are disposed inparallel with each other. At one end of each common electrode 113, theconnection pad 113A to be connected to the peripheral circuit 40 isformed (refer to FIG. 25).

The detection electrodes 25 and 26 have configurations similar to thoseof the foregoing embodiments. That is, the shapes of the detectionelectrodes 25 and 26 are different from each other. For example, theprojection part 25B does not always have to have a rod-like shape asshown in FIG. 25, but may have an annular shape as shown in FIG. 26.Also, three projection parts 25B may be provided in each region facingthe scan electrode (common electrode) 113 as shown in FIG. 25, or twoprojection parts 25B may be provided in each region facing the scanelectrode (common electrode) 113 as shown in FIG. 27.

[Peripheral Circuit 40]

In the present embodiment, the peripheral circuit 40 has the scan linedrive circuit (common line drive circuit) 47 in place of the scan linedrive circuit 45. The scan line drive circuit 47 sequentially applies aselection pulse to the plurality of common connection lines COMaccording to (synchronously with) input of the control signal 42A tosequentially select the plurality of common electrodes 113 on the basisof the common connection line COM. At the time of selecting the commonelectrode 113, the scan line drive circuit 47 performs inversion drivingof inverting a polarity of a voltage to be supplied to the commonconnection line COM at every predetermined cycle. For example, when thesignal line drive circuit 45 performs 1H inversion driving, the scanline drive circuit 47 applies a potential, whose polarity relative to areference potential becomes opposite to the polarity relative to thereference potential, of the signal line DTL to the common connectionline COM corresponding to the selected pixels 11 selected by the scanline drive circuit 44.

[Operation]

An example of the operation of the liquid crystal display device 2according to the present embodiment will now be described.

In the liquid crystal display device 2, the signal potentialcorresponding to the video signal 40A is applied to the signal lines DTLby the signal line drive circuit 43, and the selection pulse accordingto the control signal 42A is sequentially applied to the plurality ofscan lines WSL1 by the scan line drive circuit 44. Consequently, atransverse electric field having a magnitude corresponding to the signalpotential is applied on the pixel 11 unit basis to the liquid crystallayer 130, and the liquid crystal molecules are aligned in apredetermined direction. Therefore, the light from the backlight 30 ismodulated on the pixel 11 unit basis in the liquid crystal layer 130 inaccordance with the alignment direction of the liquid crystal molecules.As a result, an image is displayed on the image display face 2A.

In the liquid crystal display device 2, further, the selection pulse issequentially applied to the plurality of common connection lines COM bythe scan line drive circuit 47. Thus, capacitive elements (capacitiveelements corresponding to the capacitive elements 104) each formed inthe intersection part of the common electrode 113 and the detectionelectrode 25 are sequentially changed/discharged, and a detection signalV_(det) of a level based on the capacitance value of the capacitiveelement is output from each of the plurality of detection electrodes 25.The outputs (detection signals V_(det)) from the plurality of detectionelectrodes 25 are input to the detection circuit 46. In a state where afinger of the user is not in contact with the surface of the touch panel60, the level of the detection signal V_(det) is almost constant.

When a finger of the user touches any place in the surface of the touchpanel 60, a capacitive element formed by an object such as the finger (acapacitive element corresponding to the capacitive element 109) is addedto the capacitive element formed in the position where the finger or thelike is touched. Consequently, a value of the detection signal V_(det)output from the detection electrode 25 when the selection pulse isapplied to the common electrode 113 corresponding to the touch positionbecomes smaller than a value of the detection signal V_(det) output whenthe selection pulse is applied to another place. In the detectioncircuit 46, the detection signal V_(det) is compared with a thresholdvoltage V_(th). For example, when the detection signal V_(det) is equalto or less than the threshold voltage V_(th), it is determined that thefinger of the user or the like is in contact with the surface of thetouch panel 60. The contact position is determined from the applicationtiming of the selection pulse and the detection timing of the detectionsignal V_(det) which is equal to or less than the threshold voltageV_(th) in the detection circuit 46.

[Effects]

Next, the effects of the liquid crystal display device 2 according tothe present embodiment will be described.

In the present embodiment, the two kinds of the detection electrodes 25and 26 having different line widths are provided for the liquid crystaldisplay panel 60, as one of the electrodes of the touch sensor of theelectrostatic capacitance type used for detecting thecontact/non-contact state. The detection electrodes 25 and 26 aredisposed opposing to the scan electrode (common electrode) 113 via apredetermined gap. Thus, when voltage is applied between the scanelectrode (common electrode) 113 and the detection electrodes 25 and 26,for example, lines of electric force as illustrated in FIG. 28 aregenerated between the scan electrode (common electrode) 113 and thedetection electrodes 25 and 26. In the gap between the scan electrode(common electrode) 113 and the detection electrodes 25 and 26, the linesof electric force extend almost straight. By the electric fieldsgenerated in the gap, a parallel plate capacitance C₁ is formed. On theother hand, around the gap between the scan electrode 113 and thedetection electrodes 25 and 26, the lines of electric force extendlargely around the top face side of the detection electrodes 25 and 26,and extend to the observer side more than the image display face 2A withwhich a finger or the like comes in contact. By the round electricfield, a fringe capacitance C₂ is formed.

Although the parallel plate capacitance C₁ and the fringe capacitance C₂are formed for both of the detection electrodes 25 and 26, a region inwhich the parallel plate capacitance C₁ is formed in the detectionelectrode 25 having a narrower line width is smaller than that of thedetection electrode 26 having a wider line width. That is, a value ofthe parallel plate capacitance C₁ in the detection electrode 25 issmaller than that in the detection electrode 26. On the other hand, asize of a region in which the fringe capacitance C₂ is formed largelydoes not have the relation with the line width, and is proportional tothe length of the edge of the detection electrodes 25 and 26. Forexample, as shown in FIGS. 25, 26, and 27, in the case where thedetection electrode 25 is provided with the projection parts 25B, theregion in which the fringe capacitance C₂ is formed in the detectionelectrode 25 is wider than that of the detection electrode 26 by theamount of the length of the edge included in the projection part 25B.Therefore, a ratio of the fringe capacitance C₂ in the capacitance(total capacitance) obtained by adding the parallel plate capacitance C₁and the fringe capacitance C₂ in the detection electrode 25 is higherthan that in the detection electrode 26.

It is now assumed that a finger or the like is brought close to thedetection electrodes 25 and 26 and interrupts the electric field formingthe fringe capacitance C₂. Due to the interruption with the finger orthe like, the fringe capacitance C₂ decreases and, in associationtherewith, the total capacitance also decreases. A fluctuation rate(decrease rate) of the total capacitance in the detection electrode 25is higher than that of the detection electrode 26. Therefore, when theplurality of scan electrodes 113 are selected in desired unit, thesignal level of the detection signal V_(det) obtained from the detectionelectrode 25 fluctuates largely between the time when the finger or thelike touches the image display face 2A and the time when the finger orthe like does not touch the image display face 2A. On the other hand,the signal level of the detection signal V_(det) obtained from thedetection electrode 26 fluctuates only by a fluctuation amount smallerthan the fluctuation amount in the detection electrode 25, between thetime when the finger or the like touches the image display face 2A andthe time when the finger or the like does not touch the image displayface 2A.

As described above, in the present embodiment, the sensitivity to touchof a finger or the like in the detection electrode 25 is higher thanthat in the detection electrode 26. Further, the sensitivity to touch ofa finger or the like of the detection electrode 25 is constantregardless of the scan electrode (common electrode) 113. Similarly, thesensitivity of the detection electrode 26 is almost constant regardlessof the scan electrode (common electrode) 113. In other words, in thepresent embodiment, the detection electrodes 25 and 26 having differentsensitivities to touch of a finger or the like are provided for thetouch panel 60.

Also, in the present embodiment, the detection electrodes 25 and 26 areformed so that, for example, when the object such as a finger or pentouches the image display face 2A, the capacitance (capacitance C)formed between the detection electrode 25 and the object, and thecapacitance (capacitance D) formed between the detection electrode 26and the object, are almost equalized. In the present embodiment, forexample, as shown in FIGS. 25, 26, and 27, in the case where thedetection electrodes 25 and 26 are disposed alternately in the rowdirection, or disposed so that the projection parts 25B of the detectionelectrode 25 are closer to the neighboring detection electrode 26 morethan the electrode parts of the detection electrode 25, the capacitanceC and the capacitance D are almost equalized. In the present embodiment,for example, as shown in FIGS. 25, 26, and 27, also in the case wherethe area of the part facing one scan electrode 22 in the detectionelectrode 25 and the area of the part facing one scan electrode 22 inthe detection electrode 26 are equalized, the capacitance C and thecapacitance D are almost equalized.

Consequently, for example, sensitivity to external noise in thedetection electrode 25 and that in the detection electrode 26 are almostequalized when the user becoming as an antenna and catching the externalnoise touches the panel with his/her finger and the external noise istransmitted to the liquid crystal display panel 60 via the finger. Inthe case where the sensitivity to the external noise of the detectionelectrode 25 and the sensitivity to the external noise of the detectionelectrode 26 are equal to each other, the signal level of the externalnoise included in the detection signal V_(det) obtained from thedetection electrode 25 and that of the external noise included in thedetection signal V_(det) obtained from the detection electrode 26 areequal to each other. Therefore, for example, by calculating thedifference between the detection signal V_(det) obtained from thedetection electrode 25 and that obtained from the detection electrode26, the external noise is eliminated from the detection signals.

From the above, by providing the two kinds of the detection electrodes25 and 26 having the different sensitivities to the contact/non-contactstate and having the almost equal sensitivities to the external noise,the external noise is eliminated from the detection signal V_(det) onlyby calculating the difference of the detection signals V_(det).Therefore, it is possible to eliminate the erroneous detection caused bythe external noise.

Modifications of Fifth Embodiment [Modification 1]

Although the case where one common electrode 113 is connected to onecommon connection line COM has been described in the fifth embodiment,the plurality of neighboring common electrodes 114 may be connected toone common connection line COM. In such a case, as compared with thecase where one common electrode 113 is connected to one commonconnection line COM, the signal level of the detection signal V_(det)obtained from the detection electrodes 25 and 26 is made higher.

[Modification 2]

In the fifth embodiment, the detection electrodes 25 and 26 are formedso that the capacitances C and D become almost equal to each other.However, for example, due to manufacture error or the like, there may bea case that the capacitances C and D are slightly different from eachother. Also, for example, in the case where the projection parts 25B ofthe detection electrode 25 are eliminated and the detection electrode 25is formed in a rod-like shape as illustrated in FIG. 29, thecapacitances C and D are largely different from each other. On theassumption of those cases, as means for ensuring that the erroneousdetection caused by the external noise is eliminated, for example, theoutput adjustment circuit 56 as shown in FIG. 16, may be furtherprovided. With this configuration, the external noise is eliminated fromthe detection signal V_(det) only by calculating the difference betweentwo signals output from the output adjustment circuit 56. Therefore, itis possible to eliminate the erroneous detection caused by the externalnoise.

Sixth Embodiment

FIG. 30 illustrates an example of the top face configuration of theliquid crystal display panel 60 included in a liquid crystal displaydevice according to a sixth embodiment of the invention. The liquidcrystal display device according to the sixth embodiment is differentfrom the configuration of the liquid crystal display device 2 accordingto the fifth embodiment, in that a plurality of detection electrodes 27are provided in place of the plurality of detection electrodes 25, and aplurality of detection electrodes 28 are provided in place of theplurality of detection electrodes 26 in the liquid crystal display panel60.

The detection electrodes 27 and 28 have configurations similar to thoseof the detection electrodes 27 and 28 in the second embodiment. That is,also in the sixth embodiment, the shapes of the detection electrodes 27and 28 are different from each other. The sensitivity to touch of afinger or the like of the detection electrode 27 and that of thedetection electrode 28 are different from each other depending on thescan electrode 22. On the other hand, the sensitivity to external noiseof the detection electrode 27 and that of the detection electrode 28 arealmost equal to each other. Consequently, the external noise is removedfrom the detection signals V_(det) only by calculating the differencebetween the detection signals V_(det). Therefore, it is possible toeliminate the erroneous detection caused by the external noise.

Modifications of Sixth Embodiment [Modification 1]

Although the case where one common electrode 113 is connected to onecommon connection line COM has been described in the sixth embodiment,the plurality of neighboring common electrodes 113 may be connected toone common connection line COM. In such a case, as compared with thecase where one common electrode 113 is connected to one commonconnection line COM, the signal level of the detection signal V_(det)obtained from the detection electrodes 27 and 28 is made higher.

[Modification 2]

In the sixth embodiment, the detection electrodes 27 and 28 are formedso that the capacitances C and D become almost equal to each other.However, for example, due to manufacture error or the like, there may bea case that the capacitances C and D are slightly different from eachother. On the assumption of such a case, as means for ensuring that theerroneous detection caused by the external noise is eliminated, forexample, the output adjustment circuit 56 as shown in FIG. 16, may befurther provided. With this configuration, the external noise iseliminated from the detection signal V_(det) only by calculating thedifference between two signals output from the output adjustment circuit56. Therefore, it is possible to eliminate the erroneous detectioncaused by the external noise.

Application Examples

Hereinbelow, application examples of the display device with the touchsensor described in the foregoing embodiments and modifications will bedescribed with reference to FIGS. 31 to 35G. The display devicesaccording to the foregoing embodiments and the modifications areapplicable to electronic devices in all of fields such as a televisionapparatus, a digital camera, a notebook-sized personal computer, aportable terminal device such as a cellular phone, and a video camera.In other words, the display devices according to the embodiments and themodifications are applicable to electronic devices in all of fields,which display a video signal input from the outside or a video signalgenerated internally as an image or a video image.

Application Example 1

FIG. 31 illustrates the appearance of a television apparatus to whichthe display device according to any of the embodiments and themodifications is applied. The television apparatus has, for example, avideo display screen 300 including a front panel 310 and a filter glass320. The video display screen 300 is structured by the display deviceaccording to any of the embodiments and the modifications.

Application Example 2

FIGS. 32A and 32B illustrate the appearance of a digital camera to whichthe display device according to any of the embodiments and themodifications is applied. The digital camera has, for example, a lightemission unit 410 for flash, a display section 420, a menu switch 430,and a shutter-release button 440. The display section 420 is structuredby the display device according to any of the foregoing embodiments andthe modifications.

Application Example 3

FIG. 33 illustrates the appearance of a notebook-sized personal computerto which the display device according to any of the foregoingembodiments and the modifications is applied. The notebook-sizedpersonal computer has, for example, a body 510, a keyboard 520 foroperation of entering characters and the like, and a display section 530for displaying an image. The display section 530 is structured by thedisplay device according to any of the foregoing embodiments and themodifications.

Application Example 4

FIG. 34 illustrates the appearance of a video camera to which thedisplay device according to any of the embodiments and the modificationsis applied. The video camera has, for example, a body 610, a lens 620provided on the front face of the body 610 for photographing an object,a photographing start-stop switch 630, and a display section 640. Thedisplay section 640 is structured by the display device according to anyof the embodiments and the modifications.

Application Example 5

FIGS. 35A to 35G illustrate the appearance of a cellular phone to whichthe display device according to any of the embodiments and themodifications is applied. The cellular phone is obtained by, forexample, coupling an upper-side casing 710 and a lower-side casing 720via a coupling unit (hinge) 730, and has a display 740, a sub-display750, a picture light 760, and a camera 770. The display 740 or thesub-display 750 is structured by the display device according to any ofthe embodiments and the modifications.

The present invention has been described above with reference to theembodiments and their modifications and application examples. However,the invention is not limited to the embodiments, the modifications, andthe application examples, but may be variously modified.

For example, although the case of using the transmission-type element asthe liquid crystal display element has been described in the foregoingembodiments, the modifications, and the application examples, an elementother than the transmission type, for example, a reflection-typeelement, may be used. In this case, the light source (backlight 30) iseliminated, or the light source is disposed on the top face side of theliquid crystal display element.

Although the case of applying any of the foregoing embodiments, themodifications, and the application examples to the display device usingthe liquid crystal display element as the display element has beendescribed, the foregoing embodiments, the modifications, and theapplication examples are also applicable to a display device using adisplay element other than the liquid crystal display element, such asan organic EL element.

The series of processes described in the foregoing embodiments, themodifications, and the application examples may be performed by hardwareor software. In the case of performing the series of processes bysoftware, a program configuring the software is installed in a generalcomputer or the like. Such a program may be preliminarily recorded on arecording medium built in the computer.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-136507 filedin the Japan Patent Office on Jun. 5, 2009, the entire content of whichis hereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. A touch panel comprising: a plurality of detection scan electrodesextending in a first direction; and a plurality of detection electrodesprovided to face the plurality of detection scan electrodes andextending in a second direction which intersects the first direction,the plurality of detection electrodes having a first detection electrodeand a second detection electrode, wherein a ratio of fringe capacitanceto total capacitance between one or more selected detection scanelectrodes and the first detection electrode is different from a ratioof fringe capacitance to total capacitance between the one or moreselected detection scan electrodes and the second detection electrode,the one or more selected detection scan electrodes being selected, in adesired unit, from the plurality of detection scan electrodes, to besupplied with a selection pulse, and each of the first detectionelectrode and the second detection electrode being selected from theplurality of detection electrodes.
 2. The touch panel according to claim1, wherein the first detection electrode is disposed adjacent to thesecond detection electrode.
 3. The touch panel according to claim 1,wherein the first detection electrode is different from the seconddetection electrode in shape.
 4. The touch panel according to claim 3,wherein the first detection electrode is different from the seconddetection electrode in line width.
 5. The touch panel according to claim3, wherein a total length of an edge included in a first region of thefirst detection electrode is different from a total length of an edgeincluded in a second region of the second detection electrode, each ofthe first region and the second region facing to overlap a detectionscan electrode of the plurality of detection scan electrodes.
 6. Thetouch panel according to claim 3, wherein any one of the first andsecond detection electrodes has one or more projection parts in a regionfacing to overlap the selected detection scan electrode.
 7. The touchpanel according to claim 1, wherein shape of a detection scan electrodeof the plurality of detection scan electrodes varies according to aposition.
 8. The touch panel according to claim 7, wherein a line widthof the detection scan electrode of the plurality of detection scanelectrodes in a region facing to overlap the first detection electrodeis different from a line width of the detection scan electrode of theplurality of detection scan electrodes in a region facing to overlap thesecond detection electrode.
 9. The touch panel according to claim 7,wherein a line width of the detection scan electrode of the plurality ofdetection scan electrodes in a region facing to overlap the firstdetection electrode is equal to a line width of the detection scanelectrode of the plurality of detection scan electrodes in a regionfacing to overlap the second detection electrode, and a line width ofthe detection scan electrode of the plurality of detection scanelectrodes in a region adjacent to a region facing to overlap the firstdetection electrode is different from a line width of the detection scanelectrode of the plurality of detection scan electrodes in a regionadjacent to a region facing to overlap the second detection electrode.10. A display panel comprising: a plurality of pixel electrodes; acommon electrode provided to face the plurality of pixel electrodes; adisplay function layer having a display function; a plurality ofdetection scan electrodes extending in a first direction; and aplurality of detection electrodes provided to face the plurality ofdetection scan electrodes and extending in a second direction whichintersects the first direction, the plurality of detection electrodeshaving a first detection electrode and a second detection electrode,wherein a ratio of fringe capacitance to total capacitance between oneor more selected detection scan electrodes and the first detectionelectrode is different from a ratio of fringe capacitance to totalcapacitance between the one or more selected detection scan electrodesand the second detection electrode, the one or more selected detectionscan electrodes being selected, in a desired unit, from the plurality ofdetection scan electrodes, to be supplied with a selection pulse, andeach of the first detection electrode and the second detection electrodebeing selected from the plurality of detection electrodes.
 11. A displaypanel comprising: a plurality of pixel electrodes; a plurality of commonelectrodes provided to face the plurality of pixel electrodes andextending in a first direction; a display function layer having adisplay function; and a plurality of detection electrodes provided toface the plurality of the common electrodes and extending in a seconddirection which intersects the first direction, the plurality ofdetection electrodes having a first detection electrode and a seconddetection electrode, wherein a ratio of fringe capacitance to totalcapacitance between one or more selected common electrodes and the firstdetection electrode is different from a ratio of fringe capacitance tototal capacitance between the one or more selected common electrodes andthe second detection electrode, the one or more selected commonelectrodes being selected, in a desired unit, from the plurality ofcommon electrodes, to be supplied with a selection pulse, and each ofthe first detection electrode and the second detection electrode beingselected from the plurality of detection electrodes.
 12. A display unitcomprising: a plurality of pixel electrodes; a common electrode providedto face the plurality of pixel electrodes; a display function layerhaving a display function; a plurality of detection scan electrodesextending in a first direction; a plurality of detection electrodesprovided to face the plurality of detection scan electrodes andextending in a second direction which intersects the first direction,the plurality of detection electrodes having a first detection electrodeand a second detection electrode; a first drive section allowing thedisplay function of the display function layer to be performed byapplying a signal voltage corresponding to a video signal between eachof the pixel electrode and the common electrode; a second drive sectionapplying a selection pulse to the plurality of detection scanelectrodes; and a detection section detecting an external proximityobject on the basis of a detection signals obtained from the pluralityof detection electrodes, wherein a ratio of fringe capacitance to totalcapacitance between one or more selected detection scan electrodes andthe first detection electrode is different from a ratio of fringecapacitance to total capacitance between the one or more selecteddetection scan electrodes and the second detection electrode, the one ormore selected detection scan electrodes being selected, in a desiredunit, from the plurality of detection scan electrodes by the seconddrive section, to be supplied with a selection pulse, and each of thefirst detection electrode and the second detection electrode beingselected from the plurality of detection electrodes.
 13. The displayunit according to claim 12, wherein the detection unit detects theexternal proximity object on the basis of a difference between adetection signal obtained from the first detection electrode and adetection signal obtained from the second detection electrode.
 14. Thedisplay unit according to claim 12, wherein the detection sectioncorrects a signal level of a first detection signal or a signal level ofa second detection signal or both thereof with use of a resistor havingan adjusted resistance value which allows a value of the first detectionsignal to be equal to a value of the second detection signal, the firstand second detection signals being obtained from the first and seconddetection electrodes, respectively, when a fixed voltage is applied to apredetermined detection scan electrode selected from the plurality ofdetection scan electrodes while a conductor supplied with apredetermined voltage is in contact with an image display face, and thenthe detection section detects the external proximity object with use ofthe corrected first detection signal or the corrected second detectionsignal or both thereof.
 15. The display unit according to claim 12,wherein the detection section calculates a correction coefficient withuse of a value of the first detection signal and a value of the seconddetection signal, the first and second detection signals being obtainedfrom the first and second detection electrodes, respectively, when afixed voltage is applied to a predetermined detection scan electrodeselected from the plurality of detection scan electrodes while aconductor supplied with a predetermined voltage is in contact with animage display face, the detection section corrects a signal level of thefirst detection signal or a signal level of the second detection signalor both thereof with use of the calculated correction coefficient, andthen the detection section detects the external proximity object withuse of the corrected first detection signal or the corrected seconddetection signal or both thereof.
 16. A display unit comprising: aplurality of pixel electrodes; a plurality of common electrodes providedto face the plurality of pixel electrodes and extending in a firstdirection; a display function layer having a display function; aplurality of detection electrodes provided to face the plurality of thecommon electrodes and extending in a second direction which intersectsthe first direction, the plurality of detection electrodes having afirst detection electrode and a second detection electrode; a drivesection allowing the display function of the display function layer tobe performed by applying a signal voltage corresponding to a videosignal between each of the pixel electrode and the common electrode, andapplying a selection pulse to the plurality of common electrodes; and adetection section detecting an external proximity object on the basis ofa detection signals obtained from the plurality of detection electrodes,wherein a ratio of fringe capacitance to total capacitance between oneor more selected common electrodes and the first detection electrode isdifferent from a ratio of fringe capacitance to total capacitancebetween the one or more selected common electrodes and the seconddetection electrode, the one or more selected common electrodes beingselected, in a desired unit, from the plurality of common electrodes bythe second drive section, to be supplied with a selection pulse, andeach of the first detection electrode and the second detection electrodebeing selected from the plurality of detection electrodes.
 17. Thedisplay unit according to claim 16, wherein the detection unit detectsthe external proximity object on the basis of the difference between thedetection signal obtained from the first detection electrode and thedetection signal obtained from the second detection electrode.